upgrade: use rawsize() instead of revlog index

The revlog index is a very low-level data structure and it shouldn't
be exposed to the storage interface - at least not in its current
form.

upgrade.py is the only consumer of the index attribute on file storage
in the repository.

This commit rewrites that final consumer to use rawsize() instead of
going through the index. This is actually the more proper API to use,
as rawsize() will accurately report the size of revisions which have
a negative size in the index.

Differential Revision: https://phab.mercurial-scm.org/D4719

mercurial/filelog.py

@@ -81,7 +81,7 b' class filelog(object):'
     def iscensored(self, rev):
         return self._revlog.iscensored(rev)
 
-    # Used by verify.
+    # Used by repo upgrade, verify.
     def rawsize(self, rev):
         return self._revlog.rawsize(rev)
 

mercurial/upgrade.py

@@ -491,10 +491,7 b' def _copyrevlogs(ui, srcrepo, dstrepo, t'
         for path in rl.files():
             datasize += rl.opener.stat(path).st_size
 
-        idx = rl.index
-        for rev in rl:
-            e = idx[rev]
-            rawsize += e[2]
+        rawsize += sum(map(rl.rawsize, iter(rl)))
 
         srcsize += datasize
         srcrawsize += rawsize