actions: rename DEFICIENCY constant to FORMAT_VARIANT
It was not obvious what does deficieny means and every format change can't be a
deficiency. There are some format changes like compression levels, share-safe
which can't be understood at deficiencies.
This patch renames the constant to make things clearer.
Differential Revision: https://phab.mercurial-scm.org/D9664
Test issue2761
$ hg init
$ touch to-be-deleted
$ hg add
adding to-be-deleted
$ hg ci -m first
$ echo a > to-be-deleted
$ hg ci -m second
$ rm to-be-deleted
$ hg diff -r 0
Same issue, different code path
$ hg up -C
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ touch does-not-exist-in-1
$ hg add
adding does-not-exist-in-1
$ hg ci -m third
$ rm does-not-exist-in-1
$ hg diff -r 1