treediscovery: fix regression when run against older repos (issue2793)

I ran the entire test suite with "known" and "getbundle" disabled in
localrepository. This generated failures because the old findoutgoing
had always queried remote's heads explicitly and thus always got them
back in the returned heads. treediscovery.findcommonincoming now
correctly returns remote's heads in all cases.

Also adds a dedicated test for running treediscovery against a
pre-getbundle HTTP server.

tests/test-treediscovery.t

@@ -0,0 +1,278 b''
+Tests discovery against servers without getbundle support:
+
+  $ CAP=getbundle
+  $ . "$TESTDIR/notcapable"
+  $ echo '[ui]' >>$HGRCPATH
+  $ echo 'logtemplate="{rev} {node|short}: {desc} {branches}\\n"' >>$HGRCPATH
+  $ echo '[extensions]' >>$HGRCPATH
+  $ echo 'graphlog=' >>$HGRCPATH
+
+Setup HTTP server control:
+
+  $ export remote=http://localhost:$HGPORT/
+  $ start() {
+  >   echo '[web]' > $1/.hg/hgrc
+  >   echo 'push_ssl = false' >> $1/.hg/hgrc
+  >   echo 'allow_push = *' >> $1/.hg/hgrc
+  >   hg serve -R $1 -p $HGPORT -d --pid-file=hg.pid -E errors.log
+  >   cat hg.pid >> $DAEMON_PIDS
+  > }
+  $ stop() {
+  >   "$TESTDIR/killdaemons.py"
+  > }
+
+Both are empty:
+
+  $ hg init empty1
+  $ hg init empty2
+  $ start empty2
+  $ hg incoming -R empty1 $remote
+  comparing with http://localhost:$HGPORT/
+  no changes found
+  [1]
+  $ hg outgoing -R empty1 $remote
+  comparing with http://localhost:$HGPORT/
+  no changes found
+  [1]
+  $ hg pull -R empty1 $remote
+  pulling from http://localhost:$HGPORT/
+  no changes found
+  $ hg push -R empty1 $remote
+  pushing to http://localhost:$HGPORT/
+  no changes found
+  $ stop
+
+Base repo:
+
+  $ hg init main
+  $ cd main
+  $ hg debugbuilddag -mo '+2:tbase @name1 +3:thead1 <tbase @name2 +4:thead2 @both /thead1 +2:tmaintip'
+  $ hg glog
+  o  11 a19bfa7e7328: r11 both
+  |
+  o  10 8b6bad1512e1: r10 both
+  |
+  o    9 025829e08038: r9 both
+  |\
+  | o  8 d8f638ac69e9: r8 name2
+  | |
+  | o  7 b6b4d315a2ac: r7 name2
+  | |
+  | o  6 6c6f5d5f3c11: r6 name2
+  | |
+  | o  5 70314b29987d: r5 name2
+  | |
+  o |  4 e71dbbc70e03: r4 name1
+  | |
+  o |  3 2c8d5d5ec612: r3 name1
+  | |
+  o |  2 a7892891da29: r2 name1
+  |/
+  o  1 0019a3b924fd: r1
+  |
+  o  0 d57206cc072a: r0
+  
+  $ cd ..
+  $ start main
+
+Full clone:
+
+  $ hg clone main full
+  updating to branch default
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ cd full
+  $ hg incoming $remote
+  comparing with http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  [1]
+  $ hg outgoing $remote
+  comparing with http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  [1]
+  $ hg pull $remote
+  pulling from http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  $ hg push $remote
+  pushing to http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  $ cd ..
+
+Local is empty:
+
+  $ cd empty1
+  $ hg incoming $remote
+  comparing with http://localhost:$HGPORT/
+  0 d57206cc072a: r0 
+  1 0019a3b924fd: r1 
+  2 a7892891da29: r2 name1
+  3 2c8d5d5ec612: r3 name1
+  4 e71dbbc70e03: r4 name1
+  5 70314b29987d: r5 name2
+  6 6c6f5d5f3c11: r6 name2
+  7 b6b4d315a2ac: r7 name2
+  8 d8f638ac69e9: r8 name2
+  9 025829e08038: r9 both
+  10 8b6bad1512e1: r10 both
+  11 a19bfa7e7328: r11 both
+  $ hg outgoing $remote
+  comparing with http://localhost:$HGPORT/
+  no changes found
+  [1]
+  $ hg push $remote
+  pushing to http://localhost:$HGPORT/
+  no changes found
+  $ hg pull $remote
+  pulling from http://localhost:$HGPORT/
+  requesting all changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 12 changesets with 24 changes to 2 files
+  (run 'hg update' to get a working copy)
+  $ hg incoming $remote
+  comparing with http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  [1]
+  $ cd ..
+
+Local is subset:
+
+  $ hg clone main subset --rev name2 ; cd subset
+  adding changesets
+  adding manifests
+  adding file changes
+  added 6 changesets with 12 changes to 2 files
+  updating to branch name2
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg incoming $remote
+  comparing with http://localhost:$HGPORT/
+  searching for changes
+  6 a7892891da29: r2 name1
+  7 2c8d5d5ec612: r3 name1
+  8 e71dbbc70e03: r4 name1
+  9 025829e08038: r9 both
+  10 8b6bad1512e1: r10 both
+  11 a19bfa7e7328: r11 both
+  $ hg outgoing $remote
+  comparing with http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  [1]
+  $ hg push $remote
+  pushing to http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  $ hg pull $remote
+  pulling from http://localhost:$HGPORT/
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 6 changesets with 12 changes to 2 files
+  (run 'hg update' to get a working copy)
+  $ hg incoming $remote
+  comparing with http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  [1]
+  $ cd ..
+
+Remote is empty:
+
+  $ stop ; start empty2
+  $ cd main
+  $ hg incoming $remote
+  comparing with http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  [1]
+  $ hg outgoing $remote
+  comparing with http://localhost:$HGPORT/
+  searching for changes
+  0 d57206cc072a: r0 
+  1 0019a3b924fd: r1 
+  2 a7892891da29: r2 name1
+  3 2c8d5d5ec612: r3 name1
+  4 e71dbbc70e03: r4 name1
+  5 70314b29987d: r5 name2
+  6 6c6f5d5f3c11: r6 name2
+  7 b6b4d315a2ac: r7 name2
+  8 d8f638ac69e9: r8 name2
+  9 025829e08038: r9 both
+  10 8b6bad1512e1: r10 both
+  11 a19bfa7e7328: r11 both
+  $ hg pull $remote
+  pulling from http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  $ hg push $remote
+  pushing to http://localhost:$HGPORT/
+  searching for changes
+  remote: adding changesets
+  remote: adding manifests
+  remote: adding file changes
+  remote: added 12 changesets with 24 changes to 2 files
+  $ hg outgoing $remote
+  comparing with http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  [1]
+  $ cd ..
+
+Local is superset:
+
+  $ stop
+  $ hg clone main subset2 --rev name2
+  adding changesets
+  adding manifests
+  adding file changes
+  added 6 changesets with 12 changes to 2 files
+  updating to branch name2
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ start subset2
+  $ cd main
+  $ hg incoming $remote
+  comparing with http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  [1]
+  $ hg outgoing $remote
+  comparing with http://localhost:$HGPORT/
+  searching for changes
+  2 a7892891da29: r2 name1
+  3 2c8d5d5ec612: r3 name1
+  4 e71dbbc70e03: r4 name1
+  9 025829e08038: r9 both
+  10 8b6bad1512e1: r10 both
+  11 a19bfa7e7328: r11 both
+  $ hg pull $remote
+  pulling from http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  $ hg push $remote
+  pushing to http://localhost:$HGPORT/
+  searching for changes
+  abort: push creates new remote branches: both, name1!
+  (use 'hg push --new-branch' to create new remote branches)
+  [255]
+  $ hg push $remote --new-branch
+  pushing to http://localhost:$HGPORT/
+  searching for changes
+  remote: adding changesets
+  remote: adding manifests
+  remote: adding file changes
+  remote: added 6 changesets with 12 changes to 2 files
+  $ hg outgoing $remote
+  comparing with http://localhost:$HGPORT/
+  searching for changes
+  no changes found
+  [1]
+  $ cd ..
+
+  $ stop
+

mercurial/treediscovery.py

@@ -1,151 +1,151 b''
 # discovery.py - protocol changeset discovery functions
 #
 # Copyright 2010 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.
 
 from node import nullid, short
 from i18n import _
 import util, error
 
 def findcommonincoming(repo, remote, heads=None, force=False):
     """Return a tuple (common, fetch, heads) used to identify the common
     subset of nodes between repo and remote.
 
     "common" is a list of (at least) the heads of the common subset.
     "fetch" is a list of roots of the nodes that would be incoming, to be
       supplied to changegroupsubset.
     "heads" is either the supplied heads, or else the remote's heads.
     """
 
     m = repo.changelog.nodemap
     search = []
     fetch = set()
     seen = set()
     seenbranch = set()
     base = set()
 
     if not heads:
         heads = remote.heads()
 
     if repo.changelog.tip() == nullid:
         base.add(nullid)
         if heads != [nullid]:
             return [nullid], [nullid], list(heads)
-        return [nullid], [], []
+        return [nullid], [], heads
 
     # assume we're closer to the tip than the root
     # and start by examining the heads
     repo.ui.status(_("searching for changes\n"))
 
     unknown = []
     for h in heads:
         if h not in m:
             unknown.append(h)
         else:
             base.add(h)
 
+    if not unknown:
+        return list(base), [], list(heads)
+
     heads = unknown
-    if not unknown:
-        return list(base), [], []
-
     req = set(unknown)
     reqcnt = 0
 
     # search through remote branches
     # a 'branch' here is a linear segment of history, with four parts:
     # head, root, first parent, second parent
     # (a branch always has two parents (or none) by definition)
     unknown = remote.branches(unknown)
     while unknown:
         r = []
         while unknown:
             n = unknown.pop(0)
             if n[0] in seen:
                 continue
 
             repo.ui.debug("examining %s:%s\n"
                           % (short(n[0]), short(n[1])))
             if n[0] == nullid: # found the end of the branch
                 pass
             elif n in seenbranch:
                 repo.ui.debug("branch already found\n")
                 continue
             elif n[1] and n[1] in m: # do we know the base?
                 repo.ui.debug("found incomplete branch %s:%s\n"
                               % (short(n[0]), short(n[1])))
                 search.append(n[0:2]) # schedule branch range for scanning
                 seenbranch.add(n)
             else:
                 if n[1] not in seen and n[1] not in fetch:
                     if n[2] in m and n[3] in m:
                         repo.ui.debug("found new changeset %s\n" %
                                       short(n[1]))
                         fetch.add(n[1]) # earliest unknown
                     for p in n[2:4]:
                         if p in m:
                             base.add(p) # latest known
 
                 for p in n[2:4]:
                     if p not in req and p not in m:
                         r.append(p)
                         req.add(p)
             seen.add(n[0])
 
         if r:
             reqcnt += 1
             repo.ui.progress(_('searching'), reqcnt, unit=_('queries'))
             repo.ui.debug("request %d: %s\n" %
                         (reqcnt, " ".join(map(short, r))))
             for p in xrange(0, len(r), 10):
                 for b in remote.branches(r[p:p + 10]):
                     repo.ui.debug("received %s:%s\n" %
                                   (short(b[0]), short(b[1])))
                     unknown.append(b)
 
     # do binary search on the branches we found
     while search:
         newsearch = []
         reqcnt += 1
         repo.ui.progress(_('searching'), reqcnt, unit=_('queries'))
         for n, l in zip(search, remote.between(search)):
             l.append(n[1])
             p = n[0]
             f = 1
             for i in l:
                 repo.ui.debug("narrowing %d:%d %s\n" % (f, len(l), short(i)))
                 if i in m:
                     if f <= 2:
                         repo.ui.debug("found new branch changeset %s\n" %
                                           short(p))
                         fetch.add(p)
                         base.add(i)
                     else:
                         repo.ui.debug("narrowed branch search to %s:%s\n"
                                       % (short(p), short(i)))
                         newsearch.append((p, i))
                     break
                 p, f = i, f * 2
             search = newsearch
 
     # sanity check our fetch list
     for f in fetch:
         if f in m:
             raise error.RepoError(_("already have changeset ")
                                   + short(f[:4]))
 
     base = list(base)
     if base == [nullid]:
         if force:
             repo.ui.warn(_("warning: repository is unrelated\n"))
         else:
             raise util.Abort(_("repository is unrelated"))
 
     repo.ui.debug("found new changesets starting at " +
                  " ".join([short(f) for f in fetch]) + "\n")
 
     repo.ui.progress(_('searching'), None)
     repo.ui.debug("%d total queries\n" % reqcnt)
 
     return base, list(fetch), heads