--- a/hgext/evolve.py	Sat Aug 09 18:36:28 2014 -0400
+++ b/hgext/evolve.py	Sat Aug 09 19:12:16 2014 -0400
@@ -27,6 +27,8 @@
 from StringIO import StringIO
 import struct
 import urllib
+import re
+sha1re = re.compile(r'\b[0-9a-f]{6,40}\b')
 
 import mercurial
 from mercurial import util
@@ -909,6 +911,32 @@
     destbookmarks = repo.nodebookmarks(dest.node())
     nodesrc = orig.node()
     destphase = repo[nodesrc].phase()
+    commitmsg = orig.description()
+
+    cache = {}
+    sha1s = re.findall(sha1re, commitmsg)
+    unfi = repo.unfiltered()
+    for sha1 in sha1s:
+        ctx = None
+        try:
+            ctx = unfi[sha1]
+        except error.RepoLookupError:
+            continue
+
+        if not ctx.obsolete():
+            continue
+
+        successors = obsolete.successorssets(repo, ctx.node(), cache)
+
+        # We can't make any assumptions about how to update the hash if the
+        # cset in question was split or diverged.
+        if len(successors) == 1 and len(successors[0]) == 1:
+            newsha1 = node.hex(successors[0][0])
+            commitmsg = commitmsg.replace(sha1, newsha1[:len(sha1)])
+        else:
+            repo.ui.note(_('The stale commit message reference to %s could '
+                           'not be updated') % sha1)
+
     tr = repo.transaction('relocate')
     try:
         try:
@@ -919,7 +947,7 @@
                         'unresolved merge conflicts (see hg help resolve)')
             cmdutil.duplicatecopies(repo, orig.node(), dest.node())
             nodenew = rebase.concludenode(repo, orig.node(), dest.node(),
-                                          node.nullid)
+                                          node.nullid, commitmsg)
         except util.Abort, exc:
             class LocalMergeFailure(MergeFailure, exc.__class__):
                 pass