mercurial/cmdutil.py

--- a/mercurial/cmdutil.py	Sat Mar 03 17:08:41 2018 -0500
+++ b/mercurial/cmdutil.py	Sat Mar 03 17:09:26 2018 -0500
@@ -1478,7 +1478,7 @@
                     patch.patchrepo(ui, repo, p1, store, tmpname, strip, prefix,
                                     files, eolmode=None)
                 except error.PatchError as e:
-                    raise error.Abort(str(e))
+                    raise error.Abort(util.forcebytestr(e))
                 if opts.get('exact'):
                     editor = None
                 else: