diff -r 884b595f5195 -r 5326e4ef1dab mercurial/pure/bdiff.py
--- a/mercurial/pure/bdiff.py	Mon Oct 02 18:18:57 2017 +0100
+++ b/mercurial/pure/bdiff.py	Fri Sep 29 15:49:20 2017 +0000
@@ -60,7 +60,8 @@
 
     bin = []
     p = [0]
-    for i in a: p.append(p[-1] + len(i))
+    for i in a:
+        p.append(p[-1] + len(i))
 
     d = difflib.SequenceMatcher(None, a, b).get_matching_blocks()
     d = _normalizeblocks(a, b, d)