phases: fix advanceboundary behavior when targetphase !=0
Changeset was properly removed from upper phase but was not explicitly added to
target phase. If advanced changesets had not pwasnt in target phase they was
considered public (0-phase).
basic test for hg debugrebuildstate
$ hg init repo
$ cd repo
$ touch foo bar
$ hg ci -Am 'add foo bar'
adding bar
adding foo
$ touch baz
$ hg add baz
$ hg rm bar
$ hg debugrebuildstate
state dump after
$ hg debugstate --nodates | sort
n 644 -1 bar
n 644 -1 foo
status
$ hg st -A
! bar
? baz
C foo