--- a/hgext/evolve.py	Thu Apr 21 06:12:20 2016 +0000
+++ b/hgext/evolve.py	Mon Apr 25 16:24:42 2016 -0700
@@ -3122,23 +3122,8 @@
         ui.write_err(_('single revision specified, nothing to fold\n'))
         return 1
 
-    roots = repo.revs('roots(%ld)', revs)
-    if len(roots) > 1:
-        raise error.Abort(_("cannot fold non-linear revisions "
-                           "(multiple roots given)"))
-    root = repo[roots.first()]
-    if root.phase() <= phases.public:
-        raise error.Abort(_("cannot fold public revisions"))
-    heads = repo.revs('heads(%ld)', revs)
-    if len(heads) > 1:
-        raise error.Abort(_("cannot fold non-linear revisions "
-                           "(multiple heads given)"))
-    head = repo[heads.first()]
-    disallowunstable = not obsolete.isenabled(repo, obsolete.allowunstableopt)
-    if disallowunstable:
-        if repo.revs("(%ld::) - %ld", revs, revs):
-            raise error.Abort(_("cannot fold chain not ending with a head "\
-                               "or with branching"))
+    root, head = _foldcheck(repo, revs)
+
     wlock = lock = None
     try:
         wlock = repo.wlock()
@@ -3174,7 +3159,25 @@
     finally:
         lockmod.release(lock, wlock)
 
-
+def _foldcheck(repo, revs):
+    roots = repo.revs('roots(%ld)', revs)
+    if len(roots) > 1:
+        raise error.Abort(_("cannot fold non-linear revisions "
+                           "(multiple roots given)"))
+    root = repo[roots.first()]
+    if root.phase() <= phases.public:
+        raise error.Abort(_("cannot fold public revisions"))
+    heads = repo.revs('heads(%ld)', revs)
+    if len(heads) > 1:
+        raise error.Abort(_("cannot fold non-linear revisions "
+                           "(multiple heads given)"))
+    head = repo[heads.first()]
+    disallowunstable = not obsolete.isenabled(repo, obsolete.allowunstableopt)
+    if disallowunstable:
+        if repo.revs("(%ld::) - %ld", revs, revs):
+            raise error.Abort(_("cannot fold chain not ending with a head "\
+                               "or with branching"))
+    return root, head
 
 @eh.wrapcommand('graft')
 def graftwrapper(orig, ui, repo, *revs, **kwargs):