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

hgext/remotefilelog/remotefilelogserver.py

@@ -186,7 +186,7 b' def onetimesetup(ui):'
                         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