flagprocessors: move _flagserrorclass attribute on revlog & co...
flagprocessors: move _flagserrorclass attribute on revlog & co
This is a small duplication, and the last bit we need to get rid of the mixin.
Honestly, I am not fan of that class attribute and it mostly exist to accomodate
The simple-storage whose usage of flag processors is dumbious and that is
currently dead code anyway. However I don't want to be pulled into futher
unrelated cleaning so it is a small price to pay.
Differential Revision:
https://phab.mercurial-scm.org/D6822
