remotefilelog: fix what looks like a wrong refactoring stable

remotefilelog: fix what looks like a wrong refactoring

when various store functions started returning a revlog type as the
first element of the tuple.

Differential Revision: https://phab.mercurial-scm.org/D11243

--- a/hgext/remotefilelog/remotefilelogserver.py	Sun Aug 01 14:39:38 2021 +0200
+++ b/hgext/remotefilelog/remotefilelogserver.py	Mon Aug 02 08:06:27 2021 -0400
@@ -186,7 +186,7 @@
                         yield (t, u, e, s)
 
             for x in repo.store.topfiles():
-                if state.noflatmf and x[0][:11] == b'00manifest.':
+                if state.noflatmf and x[1][:11] == b'00manifest.':
                     continue
                 yield x