[PATCH 1 of 5] unbundle: add a small comment to clarify the 'check_heads' call

[Pierre-Yves David]

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at ens-lyon.org>
# Date 1486029064 -3600
#      Thu Feb 02 10:51:04 2017 +0100
# Node ID 9f7c2d6269c236f00bc7d8c896d6949d13cea637
# Parent  abf029200e198878a4576a87e095bd8d77d9cea9
# EXP-Topic pushcleanup
unbundle: add a small comment to clarify the 'check_heads' call

Bundle2 have its own mechanisms to check for heads (and other) changes, so push
using bundle2 are relying on the "heads" parameter of unbundle and the
'check_heads' call is not checking anything. We add a small comment to make
this clearer.

diff -r abf029200e19 -r 9f7c2d6269c2 mercurial/exchange.py
--- a/mercurial/exchange.py	Wed Feb 01 11:30:26 2017 -0600
+++ b/mercurial/exchange.py	Thu Feb 02 10:51:04 2017 +0100
@@ -1719,6 +1719,8 @@
     if url.startswith('remote:http:') or url.startswith('remote:https:'):
         captureoutput = True
     try:
+        # note: outside bundle1, 'heads' is expected to be empty and this
+        # 'check_heads' call wil be a no-op
         check_heads(repo, heads, 'uploading changes')
         # push can proceed
         if util.safehasattr(cg, 'params'):