# HG changeset patch
# User Boris Feld <boris.feld@octobus.net>
# Date 2018-09-07 15:17:33
# Node ID 51cec7fb672e0ddd923fa26b5de83f86be334335
# Parent  04b75f3a3f2ae2bcc3bee76bd571e8cc1e87539f

snapshot: also use None as a stop value for `_refinegroup`

This is yet another small step toward turning `_refinegroups` into a co-routine.

diff --git a/mercurial/revlogutils/deltas.py b/mercurial/revlogutils/deltas.py
--- a/mercurial/revlogutils/deltas.py
+++ b/mercurial/revlogutils/deltas.py
@@ -587,7 +587,11 @@ def _candidategroups(revlog, textlen, p1
     deltas_limit = textlen * LIMIT_DELTA2TEXT
 
     tested = set([nullrev])
-    for temptative in _refinedgroups(revlog, p1, p2, cachedelta):
+    candidates = _refinedgroups(revlog, p1, p2, cachedelta)
+    while True:
+        temptative = next(candidates)
+        if temptative is None:
+            break
         group = []
         for rev in temptative:
             # skip over empty delta (no need to include them in a chain)
@@ -632,6 +636,8 @@ def _refinedgroups(revlog, p1, p2, cache
         good = yield candidates
         if good is not None:
             break
+    # we have found nothing
+    yield None
 
 def _rawgroups(revlog, p1, p2, cachedelta):
     """Provides group of revision to be tested as delta base