diff mercurial/merge.py @ 27316:777f668eca70

merge: refuse update/merge if there are unresolved conflicts (BC)

We currently allow updating and merging (with --force) when there are
unresolved merge conflicts, as long as there is only one parent of the
working copy. Even worse, when updating to another revision
(linearly), if one of the unresolved files (including any conflict
markers in the working copy) can now be merged cleanly with the target
revision, the file becomes marked as resolved.

While we could potentially allow updates that affect only files that
are not in the set of unresolved files, that's considerably more work,
and we don't have a use case for it anyway. Instead, let's keep it
simple and refuse any merge or update (without -C) when there are
unresolved conflicts.

Note that test-merge-local.t explicitly checks for conflict markers
that get carried over on update. It's unclear if that was intentional
or not, but it seems bad enough that we should forbid it. The simplest
way of fixing the test case is to leave the conflict markers in place
and just mark the files resolved, so let's just do that for now.

--- a/mercurial/merge.py	Tue Dec 08 07:05:37 2015 +0000
+++ b/mercurial/merge.py	Mon Dec 07 20:43:24 2015 -0800
@@ -1341,8 +1341,12 @@
         fp1, fp2, xp1, xp2 = p1.node(), p2.node(), str(p1), str(p2)
 
         ### check phase
-        if not overwrite and len(pl) > 1:
-            raise error.Abort(_("outstanding uncommitted merge"))
+        if not overwrite:
+            if len(pl) > 1:
+                raise error.Abort(_("outstanding uncommitted merge"))
+            ms = mergestate.read(repo)
+            if list(ms.unresolved()):
+                raise error.Abort(_("outstanding merge conflicts"))
         if branchmerge:
             if pas == [p2]:
                 raise error.Abort(_("merging with a working directory ancestor"