# HG changeset patch
# User Martin von Zweigbergk <martinvonz@google.com>
# Date 1512166435 28800
# Node ID 5cc14407a739ff54739e55907760306c9a9418fe
# Parent  900ed9853017c5f56665f6c900f16e8514e77c92
amend: make a copy of "extra" to avoid mutating an input

I don't know of any problems this has caused, it just seems less
surprising.

Differential Revision: https://phab.mercurial-scm.org/D1575

diff -r 900ed9853017 -r 5cc14407a739 mercurial/cmdutil.py
--- a/mercurial/cmdutil.py	Sat Dec 02 06:32:41 2017 +0530
+++ b/mercurial/cmdutil.py	Fri Dec 01 14:13:55 2017 -0800
@@ -3137,6 +3137,8 @@
         # base     o - first parent of the changeset to amend
         wctx = repo[None]
 
+        # Copy to avoid mutating input
+        extra = extra.copy()
         # Update extra dict from amended commit (e.g. to preserve graft
         # source)
         extra.update(old.extra())