diff -r 5b34513d1117 -r f157ef7b1741 hgext/evolve.py
--- a/hgext/evolve.py	Sat Jan 30 16:53:12 2016 +0100
+++ b/hgext/evolve.py	Tue Jan 26 15:42:01 2016 -0800
@@ -949,26 +949,7 @@
     tr = repo.transaction('relocate')
     try:
         try:
-            if repo['.'].rev() != dest.rev():
-                merge.update(repo, dest, False, True, False)
-            if bmactive(repo):
-                repo.ui.status(_("(leaving bookmark %s)\n") % bmactive(repo))
-            bmdeactivate(repo)
-            if keepbranch:
-                repo.dirstate.setbranch(orig.branch())
-
-            try:
-                r = merge.graft(repo, orig, pctx, ['local', 'graft'], True)
-            except TypeError:
-                # not using recent enough mercurial
-                if len(orig.parents()) == 2:
-                    raise error.Abort(
-                        _("no support for evolving merge changesets yet"),
-                        hint=_("Redo the merge and use `hg prune <old> --succ "
-                               "<new>` to obsolete the old one"))
-
-                r = merge.graft(repo, orig, pctx, ['local', 'graft'])
-
+            r = _evolvemerge(repo, orig, dest, pctx, keepbranch)
             if r[-1]:  #some conflict
                 raise error.Abort(
                         'unresolved merge conflicts (see hg help resolve)')
@@ -3754,3 +3735,27 @@
         repo._bookmarks[book] = dest.node()
     if oldbookmarks or destbookmarks:
         repo._bookmarks.recordchange(tr)
+
+def _evolvemerge(repo, orig, dest, pctx, keepbranch):
+    """Used by the evolve function to merge dest on top of pctx.
+    return the same tuple as merge.graft"""
+    if repo['.'].rev() != dest.rev():
+       merge.update(repo, dest, False, True, False)
+    if bmactive(repo):
+       repo.ui.status(_("(leaving bookmark %s)\n") % bmactive(repo))
+    bmdeactivate(repo)
+    if keepbranch:
+       repo.dirstate.setbranch(orig.branch())
+
+    try:
+       r = merge.graft(repo, orig, pctx, ['local', 'graft'], True)
+    except TypeError:
+       # not using recent enough mercurial
+       if len(orig.parents()) == 2:
+           raise error.Abort(
+               _("no support for evolving merge changesets yet"),
+               hint=_("Redo the merge and use `hg prune <old> --succ "
+                      "<new>` to obsolete the old one"))
+
+       r = merge.graft(repo, orig, pctx, ['local', 'graft'])
+    return r