revlog: preindent some code in _enforceinlinesize

Indenting this beforehand will make a future changeset much simpler.

Differential Revision: https://phab.mercurial-scm.org/D10604

mercurial/revlog.py

@@ -1982,6 +1982,7 b' class revlog(object):'
             # its usage.
             self._writinghandles = None
 
+        if True:
         with self._indexfp(b'r') as ifh, self._datafp(b'w') as dfh:
             for r in self:
                 dfh.write(self._getsegmentforrevs(r, r, df=ifh)[1])