tests/test-merge9.t

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.

test that we don't interrupt the merge session if
a file-level merge failed

  $ hg init repo
  $ cd repo

  $ echo foo > foo
  $ echo a > bar
  $ hg ci -Am 'add foo'
  adding bar
  adding foo

  $ hg mv foo baz
  $ echo b >> bar
  $ echo quux > quux1
  $ hg ci -Am 'mv foo baz'
  adding quux1

  $ hg up -qC 0
  $ echo >> foo
  $ echo c >> bar
  $ echo quux > quux2
  $ hg ci -Am 'change foo'
  adding quux2
  created new head

test with the rename on the remote side
  $ HGMERGE=false hg merge
  merging bar
  merging foo and baz to baz
  merging bar failed!
  1 files updated, 1 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
  [1]
  $ hg resolve -l
  U bar
  R baz

test with the rename on the local side
  $ hg up -C 1
  3 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ HGMERGE=false hg merge
  merging bar
  merging baz and foo to baz
  merging bar failed!
  1 files updated, 1 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
  [1]

show unresolved
  $ hg resolve -l
  U bar
  R baz

unmark baz
  $ hg resolve -u baz

show
  $ hg resolve -l
  U bar
  U baz
  $ hg st
  M bar
  M baz
  M quux2
  ? bar.orig

re-resolve baz
  $ hg resolve baz
  merging baz and foo to baz

after resolve
  $ hg resolve -l
  U bar
  R baz

resolve all warning
  $ hg resolve
  abort: no files or directories specified
  (use --all to re-merge all unresolved files)
  [255]

resolve all
  $ hg resolve -a
  merging bar
  warning: conflicts while merging bar! (edit, then use 'hg resolve --mark')
  [1]

after
  $ hg resolve -l
  U bar
  R baz

  $ cd ..