dirstate: fix rebuild; add a test
If rebuild calls invalidate, it will just queue a (re)read of the dirstate
file, while what we really want is to empty the current state.
1 files updated, 0 files merged, 2 files removed, 0 files unresolved
resolving manifests
overwrite None partial False
ancestor 583c7b748052 local fb3948d97f07+ remote 40da226db0f0
a: remote moved to c -> m
a: remote moved to b -> m
copying a to b
copying a to c
merging a and b
my a@fb3948d97f07+ other b@40da226db0f0 ancestor a@583c7b748052
removing a
merging a and c
my a@fb3948d97f07+ other c@40da226db0f0 ancestor a@583c7b748052
0 files updated, 2 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
-- b --
0
1
2
-- c --
0
1
2