merge: replace a repo.lookup('.') by more typical repo['.'].node()
The `repo.lookup('.')` form comes from b3311e26f94f (merge: fix
--preview to show all nodes that will be merged (issue2043).,
2010-02-15). I don't know why that commit changed from `repo['.']`,
but I don't think there's any reason to do that. Note that performance
should not be a reason (anymore?), because repo.lookup() is
implemented by first creating a context object.
Differential Revision: https://phab.mercurial-scm.org/D7998
$ 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