localrepo: add hook point to invalidate everything on each command-server run
MQ extension will wrap this function to invalidate its state.
repo.invalidate cannot be wrapped for this purpose because qpush obtains
repo.lock in the middle of the operation, triggering repo.invalidate. Also,
it seems wrong to obtain lock earlier because mq data is non-store parts.
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