tests/test-push-checkheads-multibranches-E1.t

copies: fix the changeset based algorithm regarding merge

In 99ebde4fec99, we changed the list of files stored into the `files` field.
This lead to the changeset centric copy algorithm to break in various merge
situation involving merge. Older information could reach the merge through
`p1`, and while information from `p2` was strictly fresher, it would get
overwritten anyway.

We update the situation with more details about which revision introduces rename
information. This help use making the right decision in case of merge.

We are now running a more comprehensive suite of test with include this kind of
situation. The behavior differ slightly from the filelog based in a couple of
instance. There is mostly two distinct cases:

1) there are conflicting rename information in a merge (different rename history
on each side). In this case the filelog based implementation arbitrarily pick a
side based on the file-revision-number. So it depends on a local factor. The
changeset centric algorithm will use a deterministic approach, by picking the
information coming from the first parent of the merge. This is stable across
different clone.

2) rename information related to file that exist in both source and destination.
The filelog based implementation do not even try to detect these, however the
changeset centric one get them for "free" (it is simpler to detect them than
not).

The new implementation focus on correctness. Performance improvement will come
later.

Differential Revision: https://phab.mercurial-scm.org/D8244

====================================
Testing head checking code: Case E-1
====================================

Mercurial checks for the introduction of new heads on push. Evolution comes
into play to detect if existing branches on the server are being replaced by
some of the new one we push.

This case is part of a series of tests checking this behavior.

Category E: case involving changeset on multiple branch
TestCase 8: moving a branch to another location

.. old-state:
..
.. * 1-changeset on branch default
.. * 1-changeset on branch Z (above default)
..
.. new-state:
..
.. * 1-changeset on branch default
.. * 1-changeset on branch Z (rebased away from A0)
..
.. expected-result:
..
.. * push allowed
..
.. graph-summary:
..
..   B ø⇠◔ B'
..     | |
..   A ◔ |
..     |/
..     ●

  $ . $TESTDIR/testlib/push-checkheads-util.sh

Test setup
----------

  $ mkdir E1
  $ cd E1
  $ setuprepos
  creating basic server and client repo
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd client
  $ hg branch Z
  marked working directory as branch Z
  (branches are permanent and global, did you want a bookmark?)
  $ mkcommit B0
  $ hg push --new-branch
  pushing to $TESTTMP/E1/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  $ hg up 0
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ hg branch --force Z
  marked working directory as branch Z
  $ mkcommit B1
  created new head
  $ hg debugobsolete `getid "desc(B0)" ` `getid "desc(B1)"`
  1 new obsolescence markers
  obsoleted 1 changesets
  $ hg log -G --hidden
  @  c98b855401e7 (draft): B1
  |
  | x  93e5c1321ece (draft): B0
  | |
  | o  8aaa48160adc (draft): A0
  |/
  o  1e4be0697311 (public): root
  

Actual testing
--------------

  $ hg push
  pushing to $TESTTMP/E1/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  1 new obsolescence markers
  obsoleted 1 changesets

  $ cd ../..