filectx: fix return of renamed

How is this not blowing up everywhere?

It seems that filelog.renamed has always returned False (incorrectly a
boolean) instead of the assumed None. Tracing through history, you need
to skip over my move of code in 2013 by annotating from 896193a9cab4^
and you can see the original code is from 2007 (180a3eee4b75) and that
ab9fa7a85dd9 broke this by assuming renamed was a bool (instead of
None).

Refactoring memctx code later exposed this bug.

hgext/largefiles/lfcommands.py

@@ -209,6 +209,10 b' def _lfconvert_addchangeset(rsrc, rdst, '
             if f in ctx.manifest():
                 fctx = ctx.filectx(f)
                 renamed = fctx.renamed()
+                if renamed is None:
+                    # the code below assumes renamed to be a boolean or a list
+                    # and won't quite work with the value None
+                    renamed = False
                 renamedlfile = renamed and renamed[0] in lfiles
                 islfile |= renamedlfile
                 if 'l' in fctx.flags():

mercurial/context.py

@@ -1052,7 +1052,7 b' class filectx(basefilectx):'
 
         renamed = self._filelog.renamed(self._filenode)
         if not renamed:
-            return renamed
+            return None
 
         if self.rev() == self.linkrev():
             return renamed