mq: add an '-e/--exact' option to qpush

This patch adds an '--exact/-e' option to qpush that will try to push the
patches in the correct location in the DAG.  Specifying this option does the
following:

* If --move is specified, abort. It makes no sense to move a patch to the front
  of the queue and try to apply it to its parent, because its parent is one of
  the patches we just moved it in front of!
* If patches are already applied, abort. We don't want patch changesets
  scattered throughout the DAG.
* If local changes are present, abort unless --force is used, as usual.
* Find the first patch we're going to push (if we're pushing multiple patches
  with a target or --all).
* If that patch doesn't have a parent, abort, obviously.
* If the parent doesn't exist in the repo, abort.  Something is wrong.
* Update to the parent, then continue pushing the patches as normal.

tests/test-mq-qpush-exact.t

@@ -0,0 +1,290 b''
+  $ echo "[extensions]" >> $HGRCPATH
+  $ echo "mq=" >> $HGRCPATH
+  $ echo "graphlog=" >> $HGRCPATH
+
+make a test repository that looks like this:
+
+o    2:28bc7b1afd6a
+|
+| @  1:d7fe2034f71b
+|/
+o    0/62ecad8b70e5
+
+  $ hg init r0
+  $ cd r0
+  $ touch f0
+  $ hg ci -m0 -Aq
+  $ touch f1
+  $ hg ci -m1 -Aq
+
+  $ hg update 0 -q
+  $ touch f2
+  $ hg ci -m2 -Aq
+  $ hg update 1 -q
+
+make some patches with a parent: 1:d7fe2034f71b -> p0 -> p1
+
+  $ echo cp0 >> fp0
+  $ hg add fp0
+  $ hg qnew p0 -d "0 0"
+
+  $ echo cp1 >> fp1
+  $ hg add fp1
+  $ hg qnew p1 -d "0 0"
+
+  $ hg qpop -aq
+  patch queue now empty
+
+qpush --exact when at the parent
+
+  $ hg update 1 -q
+  $ hg qpush -e
+  applying p0
+  now at: p0
+  $ hg parents -qr qbase
+  1:d7fe2034f71b
+  $ hg qpop -aq
+  patch queue now empty
+
+  $ hg qpush -e p0
+  applying p0
+  now at: p0
+  $ hg parents -qr qbase
+  1:d7fe2034f71b
+  $ hg qpop -aq
+  patch queue now empty
+
+  $ hg qpush -e p1
+  applying p0
+  applying p1
+  now at: p1
+  $ hg parents -qr qbase
+  1:d7fe2034f71b
+  $ hg qpop -aq
+  patch queue now empty
+
+  $ hg qpush -ea
+  applying p0
+  applying p1
+  now at: p1
+  $ hg parents -qr qbase
+  1:d7fe2034f71b
+  $ hg qpop -aq
+  patch queue now empty
+
+qpush --exact when at another rev
+
+  $ hg update 0 -q
+  $ hg qpush -e
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  applying p0
+  now at: p0
+  $ hg parents -qr qbase
+  1:d7fe2034f71b
+  $ hg qpop -aq
+  patch queue now empty
+
+  $ hg update 0 -q
+  $ hg qpush -e p0
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  applying p0
+  now at: p0
+  $ hg parents -qr qbase
+  1:d7fe2034f71b
+  $ hg qpop -aq
+  patch queue now empty
+
+  $ hg update 0 -q
+  $ hg qpush -e p1
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  applying p0
+  applying p1
+  now at: p1
+  $ hg parents -qr qbase
+  1:d7fe2034f71b
+  $ hg qpop -aq
+  patch queue now empty
+
+  $ hg update 0 -q
+  $ hg qpush -ea
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  applying p0
+  applying p1
+  now at: p1
+  $ hg parents -qr qbase
+  1:d7fe2034f71b
+  $ hg qpop -aq
+  patch queue now empty
+
+qpush --exact while crossing branches
+
+  $ hg update 2 -q
+  $ hg qpush -e
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  applying p0
+  now at: p0
+  $ hg parents -qr qbase
+  1:d7fe2034f71b
+  $ hg qpop -aq
+  patch queue now empty
+
+  $ hg update 2 -q
+  $ hg qpush -e p0
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  applying p0
+  now at: p0
+  $ hg parents -qr qbase
+  1:d7fe2034f71b
+  $ hg qpop -aq
+  patch queue now empty
+
+  $ hg update 2 -q
+  $ hg qpush -e p1
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  applying p0
+  applying p1
+  now at: p1
+  $ hg parents -qr qbase
+  1:d7fe2034f71b
+  $ hg qpop -aq
+  patch queue now empty
+
+  $ hg update 2 -q
+  $ hg qpush -ea
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  applying p0
+  applying p1
+  now at: p1
+  $ hg parents -qr qbase
+  1:d7fe2034f71b
+  $ hg qpop -aq
+  patch queue now empty
+
+qpush --exact --force with changes to an unpatched file
+
+  $ hg update 1 -q
+  $ echo c0 >> f0
+  $ hg qpush -e
+  abort: local changes found, refresh first
+  [255]
+  $ hg qpush -ef
+  applying p0
+  now at: p0
+  $ cat f0
+  c0
+  $ rm f0
+  $ touch f0
+  $ hg qpop -aq
+  patch queue now empty
+
+  $ hg update 1 -q
+  $ echo c0 >> f0
+  $ hg qpush -e p1
+  abort: local changes found, refresh first
+  [255]
+  $ hg qpush -e p1 -f
+  applying p0
+  applying p1
+  now at: p1
+  $ cat f0
+  c0
+  $ rm f0
+  $ touch f0
+  $ hg qpop -aq
+  patch queue now empty
+
+qpush --exact --force with changes to a patched file
+
+  $ hg update 1 -q
+  $ echo cp0-bad >> fp0
+  $ hg add fp0
+  $ hg qpush -e
+  abort: local changes found, refresh first
+  [255]
+  $ hg qpush -ef
+  applying p0
+  file fp0 already exists
+  1 out of 1 hunks FAILED -- saving rejects to file fp0.rej
+  patch failed, unable to continue (try -v)
+  patch failed, rejects left in working dir
+  errors during apply, please fix and refresh p0
+  [2]
+  $ cat fp0
+  cp0-bad
+  $ cat fp0.rej
+  --- fp0
+  +++ fp0
+  @@ -0,0 +1,1 @@
+  +cp0
+  $ hg qpop -aqf
+  patch queue now empty
+  $ rm fp0
+  $ rm fp0.rej
+
+  $ hg update 1 -q
+  $ echo cp1-bad >> fp1
+  $ hg add fp1
+  $ hg qpush -e p1
+  abort: local changes found, refresh first
+  [255]
+  $ hg qpush -e p1 -f
+  applying p0
+  applying p1
+  file fp1 already exists
+  1 out of 1 hunks FAILED -- saving rejects to file fp1.rej
+  patch failed, unable to continue (try -v)
+  patch failed, rejects left in working dir
+  errors during apply, please fix and refresh p1
+  [2]
+  $ cat fp1
+  cp1-bad
+  $ cat fp1.rej
+  --- fp1
+  +++ fp1
+  @@ -0,0 +1,1 @@
+  +cp1
+  $ hg qpop -aqf
+  patch queue now empty
+  $ rm fp1
+  $ rm fp1.rej
+
+qpush --exact when already at a patch
+
+  $ hg update 1
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg qpush -e p0
+  applying p0
+  now at: p0
+  $ hg qpush -e p1
+  abort: cannot push --exact with applied patches
+  [255]
+  $ hg qpop -aq
+  patch queue now empty
+
+qpush --exact --move should fail
+
+  $ hg qpush -e --move p1
+  abort: cannot use --exact and --move together
+  [255]
+
+qpush --exact a patch without a parent recorded
+
+  $ hg qpush -q
+  now at: p0
+  $ grep -v '# Parent' .hg/patches/p0 > p0.new
+  $ mv p0.new .hg/patches/p0
+  $ hg qpop -aq
+  patch queue now empty
+  $ hg qpush -e
+  abort: p0 does not have a parent recorded
+  [255]
+  $ hg qpush -e p0
+  abort: p0 does not have a parent recorded
+  [255]
+  $ hg qpush -e p1
+  abort: p0 does not have a parent recorded
+  [255]
+  $ hg qpush -ea
+  abort: p0 does not have a parent recorded
+  [255]
+

hgext/mq.py

@@ -1006,7 +1006,7 b' class queue(object):'
         raise util.Abort(_("patch %s not in series") % patch)
 
     def push(self, repo, patch=None, force=False, list=False,
-             mergeq=None, all=False, move=False):
+             mergeq=None, all=False, move=False, exact=False):
         diffopts = self.diffopts()
         wlock = repo.wlock()
         try:
@@ -1015,7 +1015,7 b' class queue(object):'
                 heads += ls
             if not heads:
                 heads = [nullid]
-            if repo.dirstate.parents()[0] not in heads:
+            if repo.dirstate.parents()[0] not in heads and not exact:
                 self.ui.status(_("(working directory not at a head)\n"))
 
             if not self.series:
@@ -1062,6 +1062,18 b' class queue(object):'
             if not force:
                 self.check_localchanges(repo)
 
+            if exact:
+                if move:
+                    raise util.Abort(_("cannot use --exact and --move together"))
+                if self.applied:
+                    raise util.Abort(_("cannot push --exact with applied patches"))
+                root = self.series[start]
+                target = patchheader(self.join(root), self.plainmode).parent
+                if not target:
+                    raise util.Abort(_("%s does not have a parent recorded" % root))
+                if not repo[target] == repo['.']:
+                    hg.update(repo, target)
+
             if move:
                 if not patch:
                     raise  util.Abort(_("please specify the patch to move"))
@@ -2338,7 +2350,8 b' def push(ui, repo, patch=None, **opts):'
         mergeq = queue(ui, repo.join(""), newpath)
         ui.warn(_("merging with queue at: %s\n") % mergeq.path)
     ret = q.push(repo, patch, force=opts.get('force'), list=opts.get('list'),
-                 mergeq=mergeq, all=opts.get('all'), move=opts.get('move'))
+                 mergeq=mergeq, all=opts.get('all'), move=opts.get('move'),
+                 exact=opts.get('exact'))
     return ret
 
 def pop(ui, repo, patch=None, **opts):
@@ -3114,6 +3127,7 b' cmdtable = {'
     "^qpush":
         (push,
          [('f', 'force', None, _('apply on top of local changes')),
+          ('e', 'exact', None, _('apply the target patch to its recorded parent')),
           ('l', 'list', None, _('list patch name in commit text')),
           ('a', 'all', None, _('apply all patches')),
           ('m', 'merge', None, _('merge from another queue (DEPRECATED)')),