snapshot: extract parent chain computation
The final step of this series is to include chain related to "prev" in the
search. Before adding that code we do some simple code movement to clarify the
next diff.
$ hg init r1
$ cd r1
$ hg ci --config ui.allowemptycommit=true -m c0
$ hg ci --config ui.allowemptycommit=true -m c1
$ hg ci --config ui.allowemptycommit=true -m c2
$ hg co -q 0
$ hg ci --config ui.allowemptycommit=true -m c3
created new head
$ hg co -q 3
$ hg merge --quiet
$ hg ci --config ui.allowemptycommit=true -m c4
$ hg log -G -T'{desc}'
@ c4
|\
| o c3
| |
o | c2
| |
o | c1
|/
o c0
>>> from mercurial.ui import ui
>>> from mercurial.hg import repository
>>> repo = repository(ui())
>>> for anc in repo.changelog.ancestors([4], inclusive=True):
... print(anc)
4
3
2
1
0