[PATCH 5 of 9 v3] bundlerevlog: use for loop over iterator instead of while True

[Augie Fackler]

# HG changeset patch
# User Augie Fackler <augie at google.com>
# Date 1470416990 14400
#      Fri Aug 05 13:09:50 2016 -0400
# Node ID 3d62ff7bd297f51e29738df0de074ee9e929b6a3
# Parent  22621301ecb69d251c4481c5ebd1b05d9ad57db4
bundlerevlog: use for loop over iterator instead of while True

The iter() builtin has a neat pattern where you give it a callable of
no arguments and a sentinel value, and you can then loop over the
function calls like a normal iterator. This cleans up the code a
little.

diff --git a/mercurial/bundlerepo.py b/mercurial/bundlerepo.py
--- a/mercurial/bundlerepo.py
+++ b/mercurial/bundlerepo.py
@@ -56,10 +56,8 @@ class bundlerevlog(revlog.revlog):
         self.repotiprev = n - 1
         chain = None
         self.bundlerevs = set() # used by 'bundle()' revset expression
-        while True:
-            chunkdata = bundle.deltachunk(chain)
-            if not chunkdata:
-                break
+        getchunk = lambda: bundle.deltachunk(chain)
+        for chunkdata in iter(getchunk, {}):
             node = chunkdata['node']
             p1 = chunkdata['p1']
             p2 = chunkdata['p2']