rebase: stop clearing on-disk mergestate when running in memory
In-memory merge no longer uses on-disk mergestate since
19590b126764
(merge: use in-memory mergestate when using in-memory context,
2020-09-15). This patch removes the clearing from two places in the
in-memory rebase code. I've verified that the one with a TODO was
indeed fixed by the aforementioned commit. The other instance doesn't
seem to have any test coverage, but I'm pretty confident it's also
safe to remove.
Differential Revision: https://phab.mercurial-scm.org/D9057
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