repair: refactor broken linkrev collection

repair: refactor broken linkrev collection

This refactors broken linkrev collection such that manifest collection is in a
separate function. This allows extensions to replace the manifest collection
with a non-revlog oriented version.

I considered moving the collect changes function onto the manifestlog itself, so
it would be behind the abstraction, but since the store we're building doesn't
even have the concept of strip, embeding that concept in the manifestlog api
seemed odd.

Differential Revision: https://phab.mercurial-scm.org/D291

--- a/mercurial/repair.py	Tue Jul 25 22:53:44 2017 -0400
+++ b/mercurial/repair.py	Tue Aug 08 17:25:38 2017 -0700
@@ -67,16 +67,20 @@
 
     return sorted(files)
 
+def _collectrevlog(revlog, striprev):
+    _, brokenset = revlog.getstrippoint(striprev)
+    return [revlog.linkrev(r) for r in brokenset]
+
+def _collectmanifest(repo, striprev):
+    return _collectrevlog(repo.manifestlog._revlog, striprev)
+
 def _collectbrokencsets(repo, files, striprev):
     """return the changesets which will be broken by the truncation"""
     s = set()
-    def collectone(revlog):
-        _, brokenset = revlog.getstrippoint(striprev)
-        s.update([revlog.linkrev(r) for r in brokenset])
 
-    collectone(repo.manifestlog._revlog)
+    s.update(_collectmanifest(repo, striprev))
     for fname in files:
-        collectone(repo.file(fname))
+        s.update(_collectrevlog(repo.file(fname), striprev))
 
     return s