vfs: use 'vfs' module directly in 'mercurial.unionrepo'
Now that the 'vfs' classes moved in their own module, lets use the new module
directly. We update code iteratively to help with possible bisect needs in the
future.
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ echo qqq>qqq.txt
rollback dry run without rollback information
$ hg rollback
no rollback information available
[1]
add file
$ hg add
adding qqq.txt
commit first revision
$ hg ci -m 1
set bookmark
$ hg book test
$ echo www>>qqq.txt
commit second revision
$ hg ci -m 2
set bookmark
$ hg book test2
update to -2 (deactivates the active bookmark)
$ hg update -r -2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(leaving bookmark test2)
$ echo eee>>qqq.txt
commit new head
$ hg ci -m 3
created new head
bookmarks updated?
$ hg book
test 1:25e1ee7a0081
test2 1:25e1ee7a0081
strip to revision 1
$ hg strip 1
saved backup bundle to $TESTTMP/.hg/strip-backup/*-backup.hg (glob)
list bookmarks
$ hg book
test 0:5c9ad3787638
test2 0:5c9ad3787638