--- a/mercurial/mdiff.py
+++ b/mercurial/mdiff.py
@@ -67,7 +67,11 @@ def diff(a, b, sorted=0):
for i in a: p.append(p[-1] + len(i))
if sorted:
- d = sortdiff(a, b)
+ try:
+ d = sortdiff(a, b)
+ except:
+ print a, b
+ raise
else:
d = difflib.SequenceMatcher(None, a, b).get_matching_blocks()
la = 0