Handle empty logs in repo.checksize

mercurial/revlog.py

@@ -828,7 +828,14 b' class revlog:'
         expected = 0
         if self.count():
             expected = self.end(self.count() - 1)
+        try:
         f = self.opener(self.datafile)
         f.seek(0, 2)
         actual = f.tell()
         return expected - actual
+        except IOError, inst:
+            if inst.errno == errno.ENOENT:
+                return 0
+            raise
+
+