store: add revisions to datapack in alphabetical order

Summary:
This forces the revisions in the datapack to be added in alphabetical order.
This makes the algorithm more deterministic, but otherwise has little effect.

Test Plan: Ran the tests, ran repack

Reviewers: #sourcecontrol, rmcelroy, ttung

Reviewed By: rmcelroy

Subscribers: rmcelroy

Differential Revision: https://phabricator.intern.facebook.com/D3219760

Signature: t1:3219760:1461687720:7be5fdc1419f8214c8c83074494b33214b3684ae

remotefilelog/datapack.py

@@ -372,7 +372,7 @@ class datagc(object):
     def run(self, source, target):
         ui = self.repo.ui
 
-        files = list(source.getfiles())
+        files = sorted(source.getfiles())
         count = 0
         for filename, nodes in files:
             ancestors = {}