[PATCH 1 of 8] copies: style fixes and add comment (issue4028)

[Gábor Stefanik]

# HG changeset patch
# User Gábor Stefanik <gabor.stefanik at nng.com>
# Date 1475493511 -7200
#      Mon Oct 03 13:18:31 2016 +0200
# Node ID cfc612bc0aa84bd1d6b0a3fe67ee6385e0d9685b
# Parent  1779dde4c9ef97cb242f8d501655f236f66e5439
copies: style fixes and add comment (issue4028)

diff --git a/mercurial/copies.py b/mercurial/copies.py
--- a/mercurial/copies.py
+++ b/mercurial/copies.py
@@ -331,7 +331,8 @@
     m2 = c2.manifest()
     ma = ca.manifest()
 
-    copy1, copy2, = {}, {}
+    # see checkcopies documentation below for these dicts
+    copy1, copy2 = {}, {}
     movewithdir1, movewithdir2 = {}, {}
     fullcopy1, fullcopy2 = {}, {}
     diverge = {}