# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@octobus.net>
# Date 2020-11-20 09:49:32
# Node ID cf04af3a5ef178e484b7d2ae58684e4f62c770c4
# Parent  2367937982ba4e49ea147302cb46269b6a60be77

copies: fast path no-op merge

If the two sides of the merge are the same (they come an unaltered common
ancestors) we don't need any merging.

Differential Revision: https://phab.mercurial-scm.org/D9415

diff --git a/mercurial/copies.py b/mercurial/copies.py
--- a/mercurial/copies.py
+++ b/mercurial/copies.py
@@ -366,6 +366,9 @@ def _combine_changeset_copies(
             othercopies = all_copies.get(c)
             if othercopies is None:
                 all_copies[c] = newcopies
+            elif newcopies is othercopies:
+                # nothing to merge:
+                pass
             else:
                 # we are the second parent to work on c, we need to merge our
                 # work with the other.