discovery: fix docstring of `outgoing` class
Also, introduce a more correct name `ancestorsof` for what was named
`missingheads` before. For now, we just forward `ancestorsof` to `missingheads`
until all users are changed.
There were some mistakes in the old docstring / name:
* `missingheads` (new name: `ancestorsof`) contains the revs whose ancestors
are included in the outgoing operation. It may contain non-head revs and revs
which are already on the remote, so the name "missingheads" is wrong in two
ways.
* `missing` contains only ancestors of `missingheads`, so not *all nodes*
present in local but not in remote.
* `common` might not contain all common revs, e.g. not some that are not an
ancestor of `missingheads`.
It seems like the misleading name have fostered an actual bug (issue6372),
where `outgoing.missingheads` was used assuming that it contains the heads of
the missing changesets.
$ hg init a
$ cd a
$ touch empty1
$ hg add empty1
$ hg commit -m 'add empty1'
$ touch empty2
$ hg add empty2
$ hg commit -m 'add empty2'
$ hg up -C 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ touch empty3
$ hg add empty3
$ hg commit -m 'add empty3'
created new head
$ hg heads
changeset: 2:a1cb177e0d44
tag: tip
parent: 0:1e1d9c4e5b64
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: add empty3
changeset: 1:097d2b0e17f6
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: add empty2
$ hg merge 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
Before changeset 05257fd28591, we didn't notice the
empty file that came from rev 1:
$ hg status
M empty2
$ hg commit -m merge
$ hg manifest --debug tip
b80de5d138758541c5f05265ad144ab9fa86d1db 644 empty1
b80de5d138758541c5f05265ad144ab9fa86d1db 644 empty2
b80de5d138758541c5f05265ad144ab9fa86d1db 644 empty3
$ cd ..