mercurial/obsolete.py

--- a/mercurial/obsolete.py	Tue Jun 02 15:04:39 2015 -0400
+++ b/mercurial/obsolete.py	Mon Jun 01 18:05:38 2015 +0000
@@ -1214,7 +1214,7 @@
                 localmetadata.update(rel[2])
 
             if not prec.mutable():
-                raise util.Abort("cannot obsolete immutable changeset: %s"
+                raise util.Abort("cannot obsolete public changeset: %s"
                                  % prec)
             nprec = prec.node()
             nsucs = tuple(s.node() for s in sucs)