--- a/hgext3rd/evolve/obshistory.py	Tue Jan 30 15:11:35 2018 +0530
+++ b/hgext3rd/evolve/obshistory.py	Wed Feb 14 09:46:56 2018 +0100
@@ -13,7 +13,6 @@
     commands,
     error,
     graphmod,
-    mdiff,
     patch,
     obsolete,
     node as nodemod,
@@ -172,7 +171,7 @@
     basename = "changeset-description"
     succname = "changeset-description"
 
-    d = mdiff.unidiff(basedesc, '', succdesc, '', basename, succname)
+    d = compat.strdiff(basedesc, succdesc, basename, succname)
     # mercurial 4.1 and before return the patch directly
     if not isinstance(d, tuple):
         patch = d