diff -r ddf37b6b8c3d -r 7ebf850d3166 mercurial/patch.py
--- a/mercurial/patch.py	Sat Oct 21 17:01:20 2017 +0900
+++ b/mercurial/patch.py	Sat Oct 21 16:50:57 2017 +0900
@@ -203,7 +203,7 @@
 
     # attempt to detect the start of a patch
     # (this heuristic is borrowed from quilt)
-    diffre = re.compile(br'^(?:Index:[ \t]|diff[ \t]|RCS file: |'
+    diffre = re.compile(br'^(?:Index:[ \t]|diff[ \t]-|RCS file: |'
                         br'retrieving revision [0-9]+(\.[0-9]+)*$|'
                         br'---[ \t].*?^\+\+\+[ \t]|'
                         br'\*\*\*[ \t].*?^---[ \t])',