--- a/mercurial/scmutil.py	Wed Apr 15 10:36:21 2015 -0400
+++ b/mercurial/scmutil.py	Wed Apr 15 01:18:09 2015 -0400
@@ -174,6 +174,7 @@
 
 def develwarn(tui, msg):
     """issue a developer warning message"""
+    msg = 'devel-warn: ' + msg
     if tui.tracebackflag:
         util.debugstacktrace(msg, 2)
     else: