diff: search beyond ancestor when detecting renames

This removes an optimization that was introduced in 91eb4512edd0 but was too
aggressive - as indicated by how it changed test-mq-merge.t .

We are walking filelogs to find copy sources and we can thus not be sure to hit
the base revision and find the renamed file there - it could also be in the
first ancestor of the base ... in the filelog.

We are walking the filelog and can thus not easily know when we hit the first
ancestor of the base revision and which filename to look for there. Instead, we
use _findlimit like mergecopies do: The lower bound for how far we have to go
is found from the lowest changelog revision that is an ancestor of only one of
the compared revisions. Any filelog ancestor with a revision number lower than
that revision will be the ancestor of both compared revisions, and there is
thus no reason to go further back than that.

mercurial/copies.py

@@ -1,406 +1,412 b''
 # copies.py - copy detection for Mercurial
 #
 # Copyright 2008 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 import util
 import heapq
 
 def _nonoverlap(d1, d2, d3):
     "Return list of elements in d1 not in d2 or d3"
     return sorted([d for d in d1 if d not in d3 and d not in d2])
 
 def _dirname(f):
     s = f.rfind("/")
     if s == -1:
         return ""
     return f[:s]
 
 def _findlimit(repo, a, b):
     """Find the earliest revision that's an ancestor of a or b but not both,
     None if no such revision exists.
     """
     # basic idea:
     # - mark a and b with different sides
     # - if a parent's children are all on the same side, the parent is
     #   on that side, otherwise it is on no side
     # - walk the graph in topological order with the help of a heap;
     #   - add unseen parents to side map
     #   - clear side of any parent that has children on different sides
     #   - track number of interesting revs that might still be on a side
     #   - track the lowest interesting rev seen
     #   - quit when interesting revs is zero
 
     cl = repo.changelog
     working = len(cl) # pseudo rev for the working directory
     if a is None:
         a = working
     if b is None:
         b = working
 
     side = {a: -1, b: 1}
     visit = [-a, -b]
     heapq.heapify(visit)
     interesting = len(visit)
     hascommonancestor = False
     limit = working
 
     while interesting:
         r = -heapq.heappop(visit)
         if r == working:
             parents = [cl.rev(p) for p in repo.dirstate.parents()]
         else:
             parents = cl.parentrevs(r)
         for p in parents:
             if p < 0:
                 continue
             if p not in side:
                 # first time we see p; add it to visit
                 side[p] = side[r]
                 if side[p]:
                     interesting += 1
                 heapq.heappush(visit, -p)
             elif side[p] and side[p] != side[r]:
                 # p was interesting but now we know better
                 side[p] = 0
                 interesting -= 1
                 hascommonancestor = True
         if side[r]:
             limit = r # lowest rev visited
             interesting -= 1
 
     if not hascommonancestor:
         return None
     return limit
 
 def _chain(src, dst, a, b):
     '''chain two sets of copies a->b'''
     t = a.copy()
     for k, v in b.iteritems():
         if v in t:
             # found a chain
             if t[v] != k:
                 # file wasn't renamed back to itself
                 t[k] = t[v]
             if v not in dst:
                 # chain was a rename, not a copy
                 del t[v]
         if v in src:
             # file is a copy of an existing file
             t[k] = v
 
     # remove criss-crossed copies
     for k, v in t.items():
         if k in src and v in dst:
             del t[k]
 
     return t
 
-def _tracefile(fctx, actx):
-    '''return file context that is the ancestor of fctx present in actx'''
-    stop = actx.rev()
-    am = actx.manifest()
+def _tracefile(fctx, am, limit=-1):
+    '''return file context that is the ancestor of fctx present in ancestor
+    manifest am, stopping after the first ancestor lower than limit'''
 
     for f in fctx.ancestors():
         if am.get(f.path(), None) == f.filenode():
             return f
-        if f.rev() < stop:
+        if f.rev() < limit:
             return None
 
 def _dirstatecopies(d):
     ds = d._repo.dirstate
     c = ds.copies().copy()
     for k in c.keys():
         if ds[k] not in 'anm':
             del c[k]
     return c
 
 def _forwardcopies(a, b):
     '''find {dst@b: src@a} copy mapping where a is an ancestor of b'''
 
     # check for working copy
     w = None
     if b.rev() is None:
         w = b
         b = w.p1()
         if a == b:
             # short-circuit to avoid issues with merge states
             return _dirstatecopies(w)
 
+    # files might have to be traced back to the fctx parent of the last
+    # one-side-only changeset, but not further back than that
+    limit = _findlimit(a._repo, a.rev(), b.rev())
+    if limit is None:
+        limit = -1
+    am = a.manifest()
+
     # find where new files came from
     # we currently don't try to find where old files went, too expensive
     # this means we can miss a case like 'hg rm b; hg cp a b'
     cm = {}
     missing = set(b.manifest().iterkeys())
     missing.difference_update(a.manifest().iterkeys())
 
     for f in missing:
-        ofctx = _tracefile(b[f], a)
+        ofctx = _tracefile(b[f], am, limit)
         if ofctx:
             cm[f] = ofctx.path()
 
     # combine copies from dirstate if necessary
     if w is not None:
         cm = _chain(a, w, cm, _dirstatecopies(w))
 
     return cm
 
 def _backwardrenames(a, b):
     # Even though we're not taking copies into account, 1:n rename situations
     # can still exist (e.g. hg cp a b; hg mv a c). In those cases we
     # arbitrarily pick one of the renames.
     f = _forwardcopies(b, a)
     r = {}
     for k, v in sorted(f.iteritems()):
         # remove copies
         if v in a:
             continue
         r[v] = k
     return r
 
 def pathcopies(x, y):
     '''find {dst@y: src@x} copy mapping for directed compare'''
     if x == y or not x or not y:
         return {}
     a = y.ancestor(x)
     if a == x:
         return _forwardcopies(x, y)
     if a == y:
         return _backwardrenames(x, y)
     return _chain(x, y, _backwardrenames(x, a), _forwardcopies(a, y))
 
 def mergecopies(repo, c1, c2, ca):
     """
     Find moves and copies between context c1 and c2 that are relevant
     for merging.
 
     Returns four dicts: "copy", "movewithdir", "diverge", and
     "renamedelete".
 
     "copy" is a mapping from destination name -> source name,
     where source is in c1 and destination is in c2 or vice-versa.
 
     "movewithdir" is a mapping from source name -> destination name,
     where the file at source present in one context but not the other
     needs to be moved to destination by the merge process, because the
     other context moved the directory it is in.
 
     "diverge" is a mapping of source name -> list of destination names
     for divergent renames.
 
     "renamedelete" is a mapping of source name -> list of destination
     names for files deleted in c1 that were renamed in c2 or vice-versa.
     """
     # avoid silly behavior for update from empty dir
     if not c1 or not c2 or c1 == c2:
         return {}, {}, {}, {}
 
     # avoid silly behavior for parent -> working dir
     if c2.node() is None and c1.node() == repo.dirstate.p1():
         return repo.dirstate.copies(), {}, {}, {}
 
     limit = _findlimit(repo, c1.rev(), c2.rev())
     if limit is None:
         # no common ancestor, no copies
         return {}, {}, {}, {}
     m1 = c1.manifest()
     m2 = c2.manifest()
     ma = ca.manifest()
 
     def makectx(f, n):
         if len(n) != 20: # in a working context?
             if c1.rev() is None:
                 return c1.filectx(f)
             return c2.filectx(f)
         return repo.filectx(f, fileid=n)
 
     ctx = util.lrucachefunc(makectx)
     copy = {}
     movewithdir = {}
     fullcopy = {}
     diverge = {}
 
     def _checkcopies(f, m1, m2):
         checkcopies(ctx, f, m1, m2, ca, limit, diverge, copy, fullcopy)
 
     repo.ui.debug("  searching for copies back to rev %d\n" % limit)
 
     u1 = _nonoverlap(m1, m2, ma)
     u2 = _nonoverlap(m2, m1, ma)
 
     if u1:
         repo.ui.debug("  unmatched files in local:\n   %s\n"
                       % "\n   ".join(u1))
     if u2:
         repo.ui.debug("  unmatched files in other:\n   %s\n"
                       % "\n   ".join(u2))
 
     for f in u1:
         _checkcopies(f, m1, m2)
     for f in u2:
         _checkcopies(f, m2, m1)
 
     renamedelete = {}
     renamedelete2 = set()
     diverge2 = set()
     for of, fl in diverge.items():
         if len(fl) == 1 or of in c1 or of in c2:
             del diverge[of] # not actually divergent, or not a rename
             if of not in c1 and of not in c2:
                 # renamed on one side, deleted on the other side, but filter
                 # out files that have been renamed and then deleted
                 renamedelete[of] = [f for f in fl if f in c1 or f in c2]
                 renamedelete2.update(fl) # reverse map for below
         else:
             diverge2.update(fl) # reverse map for below
 
     if fullcopy:
         repo.ui.debug("  all copies found (* = to merge, ! = divergent, "
                       "% = renamed and deleted):\n")
         for f in sorted(fullcopy):
             note = ""
             if f in copy:
                 note += "*"
             if f in diverge2:
                 note += "!"
             if f in renamedelete2:
                 note += "%"
             repo.ui.debug("   src: '%s' -> dst: '%s' %s\n" % (fullcopy[f], f,
                                                               note))
     del diverge2
 
     if not fullcopy:
         return copy, movewithdir, diverge, renamedelete
 
     repo.ui.debug("  checking for directory renames\n")
 
     # generate a directory move map
     d1, d2 = c1.dirs(), c2.dirs()
     d1.addpath('/')
     d2.addpath('/')
     invalid = set()
     dirmove = {}
 
     # examine each file copy for a potential directory move, which is
     # when all the files in a directory are moved to a new directory
     for dst, src in fullcopy.iteritems():
         dsrc, ddst = _dirname(src), _dirname(dst)
         if dsrc in invalid:
             # already seen to be uninteresting
             continue
         elif dsrc in d1 and ddst in d1:
             # directory wasn't entirely moved locally
             invalid.add(dsrc)
         elif dsrc in d2 and ddst in d2:
             # directory wasn't entirely moved remotely
             invalid.add(dsrc)
         elif dsrc in dirmove and dirmove[dsrc] != ddst:
             # files from the same directory moved to two different places
             invalid.add(dsrc)
         else:
             # looks good so far
             dirmove[dsrc + "/"] = ddst + "/"
 
     for i in invalid:
         if i in dirmove:
             del dirmove[i]
     del d1, d2, invalid
 
     if not dirmove:
         return copy, movewithdir, diverge, renamedelete
 
     for d in dirmove:
         repo.ui.debug("   discovered dir src: '%s' -> dst: '%s'\n" %
                       (d, dirmove[d]))
 
     # check unaccounted nonoverlapping files against directory moves
     for f in u1 + u2:
         if f not in fullcopy:
             for d in dirmove:
                 if f.startswith(d):
                     # new file added in a directory that was moved, move it
                     df = dirmove[d] + f[len(d):]
                     if df not in copy:
                         movewithdir[f] = df
                         repo.ui.debug(("   pending file src: '%s' -> "
                                        "dst: '%s'\n") % (f, df))
                     break
 
     return copy, movewithdir, diverge, renamedelete
 
 def checkcopies(ctx, f, m1, m2, ca, limit, diverge, copy, fullcopy):
     """
     check possible copies of f from m1 to m2
 
     ctx = function accepting (filename, node) that returns a filectx.
     f = the filename to check
     m1 = the source manifest
     m2 = the destination manifest
     ca = the changectx of the common ancestor
     limit = the rev number to not search beyond
     diverge = record all diverges in this dict
     copy = record all non-divergent copies in this dict
     fullcopy = record all copies in this dict
     """
 
     ma = ca.manifest()
 
     def _related(f1, f2, limit):
         # Walk back to common ancestor to see if the two files originate
         # from the same file. Since workingfilectx's rev() is None it messes
         # up the integer comparison logic, hence the pre-step check for
         # None (f1 and f2 can only be workingfilectx's initially).
 
         if f1 == f2:
             return f1 # a match
 
         g1, g2 = f1.ancestors(), f2.ancestors()
         try:
             f1r, f2r = f1.rev(), f2.rev()
 
             if f1r is None:
                 f1 = g1.next()
             if f2r is None:
                 f2 = g2.next()
 
             while True:
                 f1r, f2r = f1.rev(), f2.rev()
                 if f1r > f2r:
                     f1 = g1.next()
                 elif f2r > f1r:
                     f2 = g2.next()
                 elif f1 == f2:
                     return f1 # a match
                 elif f1r == f2r or f1r < limit or f2r < limit:
                     return False # copy no longer relevant
         except StopIteration:
             return False
 
     of = None
     seen = set([f])
     for oc in ctx(f, m1[f]).ancestors():
         ocr = oc.rev()
         of = oc.path()
         if of in seen:
             # check limit late - grab last rename before
             if ocr < limit:
                 break
             continue
         seen.add(of)
 
         fullcopy[f] = of # remember for dir rename detection
         if of not in m2:
             continue # no match, keep looking
         if m2[of] == ma.get(of):
             break # no merge needed, quit early
         c2 = ctx(of, m2[of])
         cr = _related(oc, c2, ca.rev())
         if cr and (of == f or of == c2.path()): # non-divergent
             copy[f] = of
             of = None
             break
 
     if of in ma:
         diverge.setdefault(of, []).append(f)

tests/test-mq-merge.t

@@ -1,173 +1,175 b''
 Setup extension:
 
   $ echo "[extensions]" >> $HGRCPATH
   $ echo "mq =" >> $HGRCPATH
   $ echo "[mq]" >> $HGRCPATH
   $ echo "git = keep" >> $HGRCPATH
 
 Test merge with mq changeset as the second parent:
 
   $ hg init m
   $ cd m
   $ touch a b c
   $ hg add a
   $ hg commit -m a
   $ hg add b
   $ hg qnew -d "0 0" b
   $ hg update 0
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg add c
   $ hg commit -m c
   created new head
   $ hg merge
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg commit -m merge
   abort: cannot commit over an applied mq patch
   [255]
   $ cd ..
 
 Issue529: mq aborts when merging patch deleting files
 
   $ checkundo()
   > {
   >     if [ -f .hg/store/undo ]; then
   >         echo ".hg/store/undo still exists"
   >     fi
   > }
 
 Commit two dummy files in "init" changeset:
 
   $ hg init t
   $ cd t
   $ echo a > a
   $ echo b > b
   $ hg ci -Am init
   adding a
   adding b
   $ hg tag -l init
 
 Create a patch removing a:
 
   $ hg qnew rm_a
   $ hg rm a
   $ hg qrefresh -m "rm a"
 
 Save the patch queue so we can merge it later:
 
   $ hg qsave -c -e
   copy $TESTTMP/t/.hg/patches to $TESTTMP/t/.hg/patches.1 (glob)
   $ checkundo
 
 Update b and commit in an "update" changeset:
 
   $ hg up -C init
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ echo b >> b
   $ hg st
   M b
   $ hg ci -m update
   created new head
 
 # Here, qpush used to abort with :
 # The system cannot find the file specified => a
   $ hg manifest
   a
   b
 
   $ hg qpush -a -m
   merging with queue at: $TESTTMP/t/.hg/patches.1 (glob)
   applying rm_a
   now at: rm_a
 
   $ checkundo
   $ hg manifest
   b
 
 Ensure status is correct after merge:
 
   $ hg qpop -a
   popping rm_a
   popping .hg.patches.merge.marker
   patch queue now empty
 
   $ cd ..
 
 Classic MQ merge sequence *with an explicit named queue*:
 
   $ hg init t2
   $ cd t2
   $ echo '[diff]' > .hg/hgrc
   $ echo 'nodates = 1' >> .hg/hgrc
   $ echo a > a
   $ hg ci -Am init
   adding a
   $ echo b > a
   $ hg ci -m changea
   $ hg up -C 0
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg cp a aa
   $ echo c >> a
   $ hg qnew --git -f -e patcha
   $ echo d >> a
   $ hg qnew -d '0 0' -f -e patcha2
 
 Create the reference queue:
 
   $ hg qsave -c -e -n refqueue
   copy $TESTTMP/t2/.hg/patches to $TESTTMP/t2/.hg/refqueue (glob)
   $ hg up -C 1
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
 
 Merge:
 
   $ HGMERGE=internal:other hg qpush -a -m -n refqueue
   merging with queue at: $TESTTMP/t2/.hg/refqueue (glob)
   applying patcha
   patching file a
   Hunk #1 succeeded at 2 with fuzz 1 (offset 0 lines).
   fuzz found when applying patch, stopping
   patch didn't work out, merging patcha
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   0 files updated, 2 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   applying patcha2
   now at: patcha2
 
 Check patcha is still a git patch:
 
   $ cat .hg/patches/patcha
   # HG changeset patch
   # Parent d3873e73d99ef67873dac33fbcc66268d5d2b6f4
   
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,1 +1,2 @@
   -b
   +a
   +c
-  diff --git a/aa b/aa
-  new file mode 100644
-  --- /dev/null
+  diff --git a/a b/aa
+  copy from a
+  copy to aa
+  --- a/a
   +++ b/aa
-  @@ -0,0 +1,1 @@
+  @@ -1,1 +1,1 @@
+  -b
   +a
 
 Check patcha2 is still a regular patch:
 
   $ cat .hg/patches/patcha2
   # HG changeset patch
   # Parent ???????????????????????????????????????? (glob)
   # Date 0 0
   
   diff -r ???????????? -r ???????????? a (glob)
   --- a/a
   +++ b/a
   @@ -1,2 +1,3 @@
    a
    c
   +d
 
   $ cd ..
 

tests/test-mv-cp-st-diff.t

@@ -1,1569 +1,1607 b''
 
   $ add()
   > {
   >     echo $2 >> $1
   > }
   $ hg init t
   $ cd t
 
 set up a boring main branch
 
   $ add a a
   $ hg add a
   $ mkdir x
   $ add x/x x
   $ hg add x/x
   $ hg ci -m0
   $ add a m1
   $ hg ci -m1
   $ add a m2
   $ add x/y y1
   $ hg add x/y
   $ hg ci -m2
   $ cd ..
 
   $ show()
   > {
   >     echo "# $2:"
   >     echo
   >     echo "% hg st -C $1"
   >     hg st -C $1
   >     echo
   >     echo "% hg diff --git $1"
   >     hg diff --git $1
   >     echo
   > }
   $ count=0
 
 make a new branch and get diff/status output
 $1 - first commit
 $2 - second commit
 $3 - working dir action
 
   $ tb()
   > {
   >     hg clone -q t t2 ; cd t2
   >     hg co -q -C 0
   > 
   >     echo % add a $count
   >     add a $count
   >     count=`expr $count + 1`
   >     echo % hg ci -m "t0"
   >     hg ci -m "t0"
   >     echo % $1
   >     $1
   >     echo % hg ci -m "t1"
   >     hg ci -m "t1"
   >     echo % $2
   >     $2
   >     echo % hg ci -m "t2"
   >     hg ci -m "t2"
   >     echo % $3
   >     $3
   >     echo
   >     show "" "working to parent"
   >     show "--rev 0" "working to root"
   >     show "--rev 2" "working to branch"
   >     show "--rev 0 --rev ." "root to parent"
   >     show "--rev . --rev 0" "parent to root"
   >     show "--rev 2 --rev ." "branch to parent"
   >     show "--rev . --rev 2" "parent to branch"
   >     echo
   >     cd ..
   >     rm -rf t2
   > }
 
 rename in working dir
 
   $ tb "add a a1" "add a a2" "hg mv a b"
   % add a 0
   % hg ci -m t0
   created new head
   % add a a1
   % hg ci -m t1
   % add a a2
   % hg ci -m t2
   % hg mv a b
   
   # working to parent:
   
   % hg st -C 
   A b
     a
   R a
   
   % hg diff --git 
   diff --git a/a b/b
   rename from a
   rename to b
   
   # working to root:
   
   % hg st -C --rev 0
   A b
     a
   R a
   
   % hg diff --git --rev 0
   diff --git a/a b/b
   rename from a
   rename to b
   --- a/a
   +++ b/b
   @@ -1,1 +1,4 @@
    a
   +0
   +a1
   +a2
   
   # working to branch:
   
   % hg st -C --rev 2
   A b
     a
   R a
   R x/y
   
   % hg diff --git --rev 2
   diff --git a/a b/b
   rename from a
   rename to b
   --- a/a
   +++ b/b
   @@ -1,3 +1,4 @@
    a
   -m1
   -m2
   +0
   +a1
   +a2
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # root to parent:
   
   % hg st -C --rev 0 --rev .
   M a
   
   % hg diff --git --rev 0 --rev .
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,1 +1,4 @@
    a
   +0
   +a1
   +a2
   
   # parent to root:
   
   % hg st -C --rev . --rev 0
   M a
   
   % hg diff --git --rev . --rev 0
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,4 +1,1 @@
    a
   -0
   -a1
   -a2
   
   # branch to parent:
   
   % hg st -C --rev 2 --rev .
   M a
   R x/y
   
   % hg diff --git --rev 2 --rev .
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,3 +1,4 @@
    a
   -m1
   -m2
   +0
   +a1
   +a2
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # parent to branch:
   
   % hg st -C --rev . --rev 2
   M a
   A x/y
   
   % hg diff --git --rev . --rev 2
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,4 +1,3 @@
    a
   -0
   -a1
   -a2
   +m1
   +m2
   diff --git a/x/y b/x/y
   new file mode 100644
   --- /dev/null
   +++ b/x/y
   @@ -0,0 +1,1 @@
   +y1
   
   
 copy in working dir
 
   $ tb "add a a1" "add a a2" "hg cp a b"
   % add a 1
   % hg ci -m t0
   created new head
   % add a a1
   % hg ci -m t1
   % add a a2
   % hg ci -m t2
   % hg cp a b
   
   # working to parent:
   
   % hg st -C 
   A b
     a
   
   % hg diff --git 
   diff --git a/a b/b
   copy from a
   copy to b
   
   # working to root:
   
   % hg st -C --rev 0
   M a
   A b
     a
   
   % hg diff --git --rev 0
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,1 +1,4 @@
    a
   +1
   +a1
   +a2
   diff --git a/a b/b
   copy from a
   copy to b
   --- a/a
   +++ b/b
   @@ -1,1 +1,4 @@
    a
   +1
   +a1
   +a2
   
   # working to branch:
   
   % hg st -C --rev 2
   M a
   A b
     a
   R x/y
   
   % hg diff --git --rev 2
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,3 +1,4 @@
    a
   -m1
   -m2
   +1
   +a1
   +a2
   diff --git a/a b/b
   copy from a
   copy to b
   --- a/a
   +++ b/b
   @@ -1,3 +1,4 @@
    a
   -m1
   -m2
   +1
   +a1
   +a2
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # root to parent:
   
   % hg st -C --rev 0 --rev .
   M a
   
   % hg diff --git --rev 0 --rev .
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,1 +1,4 @@
    a
   +1
   +a1
   +a2
   
   # parent to root:
   
   % hg st -C --rev . --rev 0
   M a
   
   % hg diff --git --rev . --rev 0
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,4 +1,1 @@
    a
   -1
   -a1
   -a2
   
   # branch to parent:
   
   % hg st -C --rev 2 --rev .
   M a
   R x/y
   
   % hg diff --git --rev 2 --rev .
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,3 +1,4 @@
    a
   -m1
   -m2
   +1
   +a1
   +a2
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # parent to branch:
   
   % hg st -C --rev . --rev 2
   M a
   A x/y
   
   % hg diff --git --rev . --rev 2
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,4 +1,3 @@
    a
   -1
   -a1
   -a2
   +m1
   +m2
   diff --git a/x/y b/x/y
   new file mode 100644
   --- /dev/null
   +++ b/x/y
   @@ -0,0 +1,1 @@
   +y1
   
   
 single rename
 
   $ tb "hg mv a b" "add b b1" "add b w"
   % add a 2
   % hg ci -m t0
   created new head
   % hg mv a b
   % hg ci -m t1
   % add b b1
   % hg ci -m t2
   % add b w
   
   # working to parent:
   
   % hg st -C 
   M b
   
   % hg diff --git 
   diff --git a/b b/b
   --- a/b
   +++ b/b
   @@ -1,3 +1,4 @@
    a
    2
    b1
   +w
   
   # working to root:
   
   % hg st -C --rev 0
   A b
     a
   R a
   
   % hg diff --git --rev 0
   diff --git a/a b/b
   rename from a
   rename to b
   --- a/a
   +++ b/b
   @@ -1,1 +1,4 @@
    a
   +2
   +b1
   +w
   
   # working to branch:
   
   % hg st -C --rev 2
   A b
     a
   R a
   R x/y
   
   % hg diff --git --rev 2
   diff --git a/a b/b
   rename from a
   rename to b
   --- a/a
   +++ b/b
   @@ -1,3 +1,4 @@
    a
   -m1
   -m2
   +2
   +b1
   +w
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # root to parent:
   
   % hg st -C --rev 0 --rev .
   A b
     a
   R a
   
   % hg diff --git --rev 0 --rev .
   diff --git a/a b/b
   rename from a
   rename to b
   --- a/a
   +++ b/b
   @@ -1,1 +1,3 @@
    a
   +2
   +b1
   
   # parent to root:
   
   % hg st -C --rev . --rev 0
   A a
     b
   R b
   
   % hg diff --git --rev . --rev 0
   diff --git a/b b/a
   rename from b
   rename to a
   --- a/b
   +++ b/a
   @@ -1,3 +1,1 @@
    a
   -2
   -b1
   
   # branch to parent:
   
   % hg st -C --rev 2 --rev .
   A b
     a
   R a
   R x/y
   
   % hg diff --git --rev 2 --rev .
   diff --git a/a b/b
   rename from a
   rename to b
   --- a/a
   +++ b/b
   @@ -1,3 +1,3 @@
    a
   -m1
   -m2
   +2
   +b1
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # parent to branch:
   
   % hg st -C --rev . --rev 2
   A a
     b
   A x/y
   R b
   
   % hg diff --git --rev . --rev 2
   diff --git a/b b/a
   rename from b
   rename to a
   --- a/b
   +++ b/a
   @@ -1,3 +1,3 @@
    a
   -2
   -b1
   +m1
   +m2
   diff --git a/x/y b/x/y
   new file mode 100644
   --- /dev/null
   +++ b/x/y
   @@ -0,0 +1,1 @@
   +y1
   
   
 single copy
 
   $ tb "hg cp a b" "add b b1" "add a w"
   % add a 3
   % hg ci -m t0
   created new head
   % hg cp a b
   % hg ci -m t1
   % add b b1
   % hg ci -m t2
   % add a w
   
   # working to parent:
   
   % hg st -C 
   M a
   
   % hg diff --git 
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,2 +1,3 @@
    a
    3
   +w
   
   # working to root:
   
   % hg st -C --rev 0
   M a
   A b
     a
   
   % hg diff --git --rev 0
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,1 +1,3 @@
    a
   +3
   +w
   diff --git a/a b/b
   copy from a
   copy to b
   --- a/a
   +++ b/b
   @@ -1,1 +1,3 @@
    a
   +3
   +b1
   
   # working to branch:
   
   % hg st -C --rev 2
   M a
   A b
     a
   R x/y
   
   % hg diff --git --rev 2
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,3 +1,3 @@
    a
   -m1
   -m2
   +3
   +w
   diff --git a/a b/b
   copy from a
   copy to b
   --- a/a
   +++ b/b
   @@ -1,3 +1,3 @@
    a
   -m1
   -m2
   +3
   +b1
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # root to parent:
   
   % hg st -C --rev 0 --rev .
   M a
   A b
     a
   
   % hg diff --git --rev 0 --rev .
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,1 +1,2 @@
    a
   +3
   diff --git a/a b/b
   copy from a
   copy to b
   --- a/a
   +++ b/b
   @@ -1,1 +1,3 @@
    a
   +3
   +b1
   
   # parent to root:
   
   % hg st -C --rev . --rev 0
   M a
   R b
   
   % hg diff --git --rev . --rev 0
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,2 +1,1 @@
    a
   -3
   diff --git a/b b/b
   deleted file mode 100644
   --- a/b
   +++ /dev/null
   @@ -1,3 +0,0 @@
   -a
   -3
   -b1
   
   # branch to parent:
   
   % hg st -C --rev 2 --rev .
   M a
   A b
     a
   R x/y
   
   % hg diff --git --rev 2 --rev .
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,3 +1,2 @@
    a
   -m1
   -m2
   +3
   diff --git a/a b/b
   copy from a
   copy to b
   --- a/a
   +++ b/b
   @@ -1,3 +1,3 @@
    a
   -m1
   -m2
   +3
   +b1
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # parent to branch:
   
   % hg st -C --rev . --rev 2
   M a
   A x/y
   R b
   
   % hg diff --git --rev . --rev 2
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,2 +1,3 @@
    a
   -3
   +m1
   +m2
   diff --git a/b b/b
   deleted file mode 100644
   --- a/b
   +++ /dev/null
   @@ -1,3 +0,0 @@
   -a
   -3
   -b1
   diff --git a/x/y b/x/y
   new file mode 100644
   --- /dev/null
   +++ b/x/y
   @@ -0,0 +1,1 @@
   +y1
   
   
 rename chain
 
   $ tb "hg mv a b" "hg mv b c" "hg mv c d"
   % add a 4
   % hg ci -m t0
   created new head
   % hg mv a b
   % hg ci -m t1
   % hg mv b c
   % hg ci -m t2
   % hg mv c d
   
   # working to parent:
   
   % hg st -C 
   A d
     c
   R c
   
   % hg diff --git 
   diff --git a/c b/d
   rename from c
   rename to d
   
   # working to root:
   
   % hg st -C --rev 0
   A d
     a
   R a
   
   % hg diff --git --rev 0
   diff --git a/a b/d
   rename from a
   rename to d
   --- a/a
   +++ b/d
   @@ -1,1 +1,2 @@
    a
   +4
   
   # working to branch:
   
   % hg st -C --rev 2
   A d
     a
   R a
   R x/y
   
   % hg diff --git --rev 2
   diff --git a/a b/d
   rename from a
   rename to d
   --- a/a
   +++ b/d
   @@ -1,3 +1,2 @@
    a
   -m1
   -m2
   +4
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # root to parent:
   
   % hg st -C --rev 0 --rev .
   A c
     a
   R a
   
   % hg diff --git --rev 0 --rev .
   diff --git a/a b/c
   rename from a
   rename to c
   --- a/a
   +++ b/c
   @@ -1,1 +1,2 @@
    a
   +4
   
   # parent to root:
   
   % hg st -C --rev . --rev 0
   A a
     c
   R c
   
   % hg diff --git --rev . --rev 0
   diff --git a/c b/a
   rename from c
   rename to a
   --- a/c
   +++ b/a
   @@ -1,2 +1,1 @@
    a
   -4
   
   # branch to parent:
   
   % hg st -C --rev 2 --rev .
   A c
     a
   R a
   R x/y
   
   % hg diff --git --rev 2 --rev .
   diff --git a/a b/c
   rename from a
   rename to c
   --- a/a
   +++ b/c
   @@ -1,3 +1,2 @@
    a
   -m1
   -m2
   +4
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # parent to branch:
   
   % hg st -C --rev . --rev 2
   A a
     c
   A x/y
   R c
   
   % hg diff --git --rev . --rev 2
   diff --git a/c b/a
   rename from c
   rename to a
   --- a/c
   +++ b/a
   @@ -1,2 +1,3 @@
    a
   -4
   +m1
   +m2
   diff --git a/x/y b/x/y
   new file mode 100644
   --- /dev/null
   +++ b/x/y
   @@ -0,0 +1,1 @@
   +y1
   
   
 copy chain
 
   $ tb "hg cp a b" "hg cp b c" "hg cp c d"
   % add a 5
   % hg ci -m t0
   created new head
   % hg cp a b
   % hg ci -m t1
   % hg cp b c
   % hg ci -m t2
   % hg cp c d
   
   # working to parent:
   
   % hg st -C 
   A d
     c
   
   % hg diff --git 
   diff --git a/c b/d
   copy from c
   copy to d
   
   # working to root:
   
   % hg st -C --rev 0
   M a
   A b
     a
   A c
     a
   A d
     a
   
   % hg diff --git --rev 0
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,1 +1,2 @@
    a
   +5
   diff --git a/a b/b
   copy from a
   copy to b
   --- a/a
   +++ b/b
   @@ -1,1 +1,2 @@
    a
   +5
   diff --git a/a b/c
   copy from a
   copy to c
   --- a/a
   +++ b/c
   @@ -1,1 +1,2 @@
    a
   +5
   diff --git a/a b/d
   copy from a
   copy to d
   --- a/a
   +++ b/d
   @@ -1,1 +1,2 @@
    a
   +5
   
   # working to branch:
   
   % hg st -C --rev 2
   M a
   A b
     a
   A c
     a
   A d
     a
   R x/y
   
   % hg diff --git --rev 2
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,3 +1,2 @@
    a
   -m1
   -m2
   +5
   diff --git a/a b/b
   copy from a
   copy to b
   --- a/a
   +++ b/b
   @@ -1,3 +1,2 @@
    a
   -m1
   -m2
   +5
   diff --git a/a b/c
   copy from a
   copy to c
   --- a/a
   +++ b/c
   @@ -1,3 +1,2 @@
    a
   -m1
   -m2
   +5
   diff --git a/a b/d
   copy from a
   copy to d
   --- a/a
   +++ b/d
   @@ -1,3 +1,2 @@
    a
   -m1
   -m2
   +5
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # root to parent:
   
   % hg st -C --rev 0 --rev .
   M a
   A b
     a
   A c
     a
   
   % hg diff --git --rev 0 --rev .
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,1 +1,2 @@
    a
   +5
   diff --git a/a b/b
   copy from a
   copy to b
   --- a/a
   +++ b/b
   @@ -1,1 +1,2 @@
    a
   +5
   diff --git a/a b/c
   copy from a
   copy to c
   --- a/a
   +++ b/c
   @@ -1,1 +1,2 @@
    a
   +5
   
   # parent to root:
   
   % hg st -C --rev . --rev 0
   M a
   R b
   R c
   
   % hg diff --git --rev . --rev 0
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,2 +1,1 @@
    a
   -5
   diff --git a/b b/b
   deleted file mode 100644
   --- a/b
   +++ /dev/null
   @@ -1,2 +0,0 @@
   -a
   -5
   diff --git a/c b/c
   deleted file mode 100644
   --- a/c
   +++ /dev/null
   @@ -1,2 +0,0 @@
   -a
   -5
   
   # branch to parent:
   
   % hg st -C --rev 2 --rev .
   M a
   A b
     a
   A c
     a
   R x/y
   
   % hg diff --git --rev 2 --rev .
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,3 +1,2 @@
    a
   -m1
   -m2
   +5
   diff --git a/a b/b
   copy from a
   copy to b
   --- a/a
   +++ b/b
   @@ -1,3 +1,2 @@
    a
   -m1
   -m2
   +5
   diff --git a/a b/c
   copy from a
   copy to c
   --- a/a
   +++ b/c
   @@ -1,3 +1,2 @@
    a
   -m1
   -m2
   +5
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # parent to branch:
   
   % hg st -C --rev . --rev 2
   M a
   A x/y
   R b
   R c
   
   % hg diff --git --rev . --rev 2
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,2 +1,3 @@
    a
   -5
   +m1
   +m2
   diff --git a/b b/b
   deleted file mode 100644
   --- a/b
   +++ /dev/null
   @@ -1,2 +0,0 @@
   -a
   -5
   diff --git a/c b/c
   deleted file mode 100644
   --- a/c
   +++ /dev/null
   @@ -1,2 +0,0 @@
   -a
   -5
   diff --git a/x/y b/x/y
   new file mode 100644
   --- /dev/null
   +++ b/x/y
   @@ -0,0 +1,1 @@
   +y1
   
   
 circular rename
 
   $ tb "add a a1" "hg mv a b" "hg mv b a"
   % add a 6
   % hg ci -m t0
   created new head
   % add a a1
   % hg ci -m t1
   % hg mv a b
   % hg ci -m t2
   % hg mv b a
   
   # working to parent:
   
   % hg st -C 
   A a
     b
   R b
   
   % hg diff --git 
   diff --git a/b b/a
   rename from b
   rename to a
   
   # working to root:
   
   % hg st -C --rev 0
   M a
   
   % hg diff --git --rev 0
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,1 +1,3 @@
    a
   +6
   +a1
   
   # working to branch:
   
   % hg st -C --rev 2
   M a
   R x/y
   
   % hg diff --git --rev 2
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,3 +1,3 @@
    a
   -m1
   -m2
   +6
   +a1
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # root to parent:
   
   % hg st -C --rev 0 --rev .
   A b
     a
   R a
   
   % hg diff --git --rev 0 --rev .
   diff --git a/a b/b
   rename from a
   rename to b
   --- a/a
   +++ b/b
   @@ -1,1 +1,3 @@
    a
   +6
   +a1
   
   # parent to root:
   
   % hg st -C --rev . --rev 0
   A a
     b
   R b
   
   % hg diff --git --rev . --rev 0
   diff --git a/b b/a
   rename from b
   rename to a
   --- a/b
   +++ b/a
   @@ -1,3 +1,1 @@
    a
   -6
   -a1
   
   # branch to parent:
   
   % hg st -C --rev 2 --rev .
   A b
     a
   R a
   R x/y
   
   % hg diff --git --rev 2 --rev .
   diff --git a/a b/b
   rename from a
   rename to b
   --- a/a
   +++ b/b
   @@ -1,3 +1,3 @@
    a
   -m1
   -m2
   +6
   +a1
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   
   # parent to branch:
   
   % hg st -C --rev . --rev 2
   A a
     b
   A x/y
   R b
   
   % hg diff --git --rev . --rev 2
   diff --git a/b b/a
   rename from b
   rename to a
   --- a/b
   +++ b/a
   @@ -1,3 +1,3 @@
    a
   -6
   -a1
   +m1
   +m2
   diff --git a/x/y b/x/y
   new file mode 100644
   --- /dev/null
   +++ b/x/y
   @@ -0,0 +1,1 @@
   +y1
   
   
 directory move
 
   $ tb "hg mv x y" "add y/x x1" "add y/x x2"
   % add a 7
   % hg ci -m t0
   created new head
   % hg mv x y
   moving x/x to y/x (glob)
   % hg ci -m t1
   % add y/x x1
   % hg ci -m t2
   % add y/x x2
   
   # working to parent:
   
   % hg st -C 
   M y/x
   
   % hg diff --git 
   diff --git a/y/x b/y/x
   --- a/y/x
   +++ b/y/x
   @@ -1,2 +1,3 @@
    x
    x1
   +x2
   
   # working to root:
   
   % hg st -C --rev 0
   M a
   A y/x
     x/x
   R x/x
   
   % hg diff --git --rev 0
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,1 +1,2 @@
    a
   +7
   diff --git a/x/x b/y/x
   rename from x/x
   rename to y/x
   --- a/x/x
   +++ b/y/x
   @@ -1,1 +1,3 @@
    x
   +x1
   +x2
   
   # working to branch:
   
   % hg st -C --rev 2
   M a
   A y/x
     x/x
   R x/x
   R x/y
   
   % hg diff --git --rev 2
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,3 +1,2 @@
    a
   -m1
   -m2
   +7
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   diff --git a/x/x b/y/x
   rename from x/x
   rename to y/x
   --- a/x/x
   +++ b/y/x
   @@ -1,1 +1,3 @@
    x
   +x1
   +x2
   
   # root to parent:
   
   % hg st -C --rev 0 --rev .
   M a
   A y/x
     x/x
   R x/x
   
   % hg diff --git --rev 0 --rev .
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,1 +1,2 @@
    a
   +7
   diff --git a/x/x b/y/x
   rename from x/x
   rename to y/x
   --- a/x/x
   +++ b/y/x
   @@ -1,1 +1,2 @@
    x
   +x1
   
   # parent to root:
   
   % hg st -C --rev . --rev 0
   M a
   A x/x
     y/x
   R y/x
   
   % hg diff --git --rev . --rev 0
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,2 +1,1 @@
    a
   -7
   diff --git a/y/x b/x/x
   rename from y/x
   rename to x/x
   --- a/y/x
   +++ b/x/x
   @@ -1,2 +1,1 @@
    x
   -x1
   
   # branch to parent:
   
   % hg st -C --rev 2 --rev .
   M a
   A y/x
     x/x
   R x/x
   R x/y
   
   % hg diff --git --rev 2 --rev .
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,3 +1,2 @@
    a
   -m1
   -m2
   +7
   diff --git a/x/y b/x/y
   deleted file mode 100644
   --- a/x/y
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -y1
   diff --git a/x/x b/y/x
   rename from x/x
   rename to y/x
   --- a/x/x
   +++ b/y/x
   @@ -1,1 +1,2 @@
    x
   +x1
   
   # parent to branch:
   
   % hg st -C --rev . --rev 2
   M a
   A x/x
     y/x
   A x/y
   R y/x
   
   % hg diff --git --rev . --rev 2
   diff --git a/a b/a
   --- a/a
   +++ b/a
   @@ -1,2 +1,3 @@
    a
   -7
   +m1
   +m2
   diff --git a/y/x b/x/x
   rename from y/x
   rename to x/x
   --- a/y/x
   +++ b/x/x
   @@ -1,2 +1,1 @@
    x
   -x1
   diff --git a/x/y b/x/y
   new file mode 100644
   --- /dev/null
   +++ b/x/y
   @@ -0,0 +1,1 @@
   +y1
   
   
 
 Cannot implement unrelated branch with tb
 testing copies with unrelated branch
 
   $ hg init unrelated
   $ cd unrelated
   $ echo a >> a
   $ hg ci -Am adda
   adding a
   $ hg mv a b
   $ hg ci -m movea
   $ hg up -C null
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ echo a >> a
   $ hg ci -Am addunrelateda
   adding a
   created new head
 
 unrelated branch diff
 
   $ hg diff --git -r 2 -r 1
   diff --git a/a b/a
   deleted file mode 100644
   --- a/a
   +++ /dev/null
   @@ -1,1 +0,0 @@
   -a
   diff --git a/b b/b
   new file mode 100644
   --- /dev/null
   +++ b/b
   @@ -0,0 +1,1 @@
   +a
   $ cd ..
+
+
+test for case where we didn't look sufficiently far back to find rename ancestor
+
+  $ hg init diffstop
+  $ cd diffstop
+  $ echo > f
+  $ hg ci -qAmf
+  $ hg mv f g
+  $ hg ci -m'f->g'
+  $ hg up -qr0
+  $ touch x
+  $ hg ci -qAmx
+  $ echo f > f
+  $ hg ci -qmf=f
+  $ hg merge -q
+  $ hg ci -mmerge
+  $ hg log -G --template '{rev}  {desc}'
+  @    4  merge
+  |\
+  | o  3  f=f
+  | |
+  | o  2  x
+  | |
+  o |  1  f->g
+  |/
+  o  0  f
+  
+  $ hg diff --git -r 2
+  diff --git a/f b/g
+  rename from f
+  rename to g
+  --- a/f
+  +++ b/g
+  @@ -1,1 +1,1 @@
+  -
+  +f
+  $ cd ..