# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@octobus.net>
# Date 2019-11-13 19:45:34
# Node ID bbd7172bc3dffea13e0de76dc09862520fd63644
# Parent  79750d7819283e47aea5c8615e755ac780951bb0

copies: show we can read data from the "first" mapping

In practice this make no difference since `t` is a copy of `a`. Having this
change before hand will make the next cleanup changeset clearer.

This is work on the road to using some native code for some performance critical
part of copy tracing.

diff --git a/mercurial/copies.py b/mercurial/copies.py
--- a/mercurial/copies.py
+++ b/mercurial/copies.py
@@ -67,7 +67,7 @@ def _chain(a, b):
     """chain two sets of copies 'a' and 'b'"""
     t = a.copy()
     for k, v in pycompat.iteritems(b):
-        t[k] = t.get(v, v)
+        t[k] = a.get(v, v)
     return t