[PATCH] patch: add close() to abstractbackend

[Martin von Zweigbergk]

# HG changeset patch
# User Martin von Zweigbergk <martinvonz at google.com>
# Date 1498838844 25200
#      Fri Jun 30 09:07:24 2017 -0700
# Node ID 7a87ec7bcd672d0aa9178d9d87a7c8433241e5d3
# Parent  40ee74bfa11122a0a3ab74186f5056243b84af89
patch: add close() to abstractbackend

patchbackend() seems to call it on an arbitrary backend, so it seems
to be part of the API. Since all subclasses do something in their
close() methods, I decided to let this one raise an exception rather
than just pass.

diff --git a/mercurial/patch.py b/mercurial/patch.py
--- a/mercurial/patch.py
+++ b/mercurial/patch.py
@@ -448,6 +448,9 @@
     def exists(self, fname):
         raise NotImplementedError
 
+    def close(self):
+        raise NotImplementedError
+
 class fsbackend(abstractbackend):
     def __init__(self, ui, basedir):
         super(fsbackend, self).__init__(ui)