diff -r 448725a2ef73 -r 61714510220d mercurial/error.py
--- a/mercurial/error.py	Fri Sep 15 00:01:57 2017 -0700
+++ b/mercurial/error.py	Sun Sep 03 16:45:33 2017 +0900
@@ -115,6 +115,9 @@
     """Raised when parsing config files and {rev,file}sets (msg[, pos])"""
     __bytes__ = _tobytes
 
+class PatchError(Exception):
+    __bytes__ = _tobytes
+
 class UnknownIdentifier(ParseError):
     """Exception raised when a {rev,file}set references an unknown identifier"""