censor: put the tuple of open files in an explicit variable

This will be simpler to pass these file around in future changesets.

Differential Revision: https://phab.mercurial-scm.org/D10897

mercurial/revlogutils/rewrite.py

@@ -246,13 +246,14 b' def v2_censor(rl, tr, censornode, tombst'
 
         # we dont need to open the old index file since its content already
         # exist in a usable form in `old_index`.
-        with all_files() as (
+        with all_files() as open_files:
+            (
             old_data_file,
             old_sidedata_file,
             new_index_file,
             new_data_file,
             new_sidedata_file,
-        ):
+            ) = open_files
             new_index_file.seek(0, os.SEEK_END)
             assert new_index_file.tell() == index_cutoff
             new_data_file.seek(0, os.SEEK_END)