py3: use b"%d" instead of str() to convert integers to bytes

Differential Revision: https://phab.mercurial-scm.org/D2664

mercurial/context.py

@@ -433,7 +433,7 b' class changectx(basectx):'
                 self._rev = changeid
                 return
             if not pycompat.ispy3 and isinstance(changeid, long):
-                changeid = str(changeid)
+                changeid = "%d" % changeid
             if changeid == 'null':
                 self._node = nullid
                 self._rev = nullrev

mercurial/revlog.py

@@ -1367,7 +1367,7 b' class revlog(object):'
         try:
             # str(rev)
             rev = int(id)
-            if str(rev) != id:
+            if "%d" % rev != id:
                 raise ValueError
             if rev < 0:
                 rev = len(self) + rev