--- a/hgext/evolve.py	Thu Nov 20 22:05:29 2014 +0100
+++ b/hgext/evolve.py	Thu Nov 20 16:12:04 2014 -0800
@@ -1576,7 +1576,7 @@
         newer = [n for n in newer if n and ctx.node() not in n]
         if newer:
             return base, tuple(ctx._repo[o] for o in newer[0])
-    raise util.Abort('base of divergent changeset not found',
+    raise util.Abort("base of divergent changeset %s not found" % ctx,
                      hint='this case is not yet handled')