tests/test-push-checkheads-superceed-A6.t

upgrade: speed up when we have only nodemap to downgrade

Similar to what we do on upgrade, if we have only persistent-nodemap to
downgrade we will just delete the nodemap files and update repository
requirements instead of processing all the revlogs.

After downgrade, we are left with unrequired docket and transaction files which
seems fine but can work on deleting them if someone feels we should.

Differential Revision: https://phab.mercurial-scm.org/D9992

====================================
Testing head checking code: Case A-6
====================================

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 A: simple case involving a branch being superceeded by another.
TestCase 6: multi-changeset branch, split on multiple other, (base on its own branch), same number of head

.. old-state:
..
.. * 2 branch (1-changeset, and 2-changesets)
..
.. new-state:
..
.. * 1 new branch superceeding the base of the old-2-changesets-branch,
.. * 1 new changesets on the old-1-changeset-branch superceeding the head of the other
..
.. expected-result:
..
.. * push allowed
..
.. graph-summary:
..
.. B'◔⇢ø B
..   | |
.. A | ø⇠◔ A'
..   | |/
.. C ● |
..    \|
..     ●

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

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

  $ mkdir A6
  $ cd A6
  $ setuprepos
  creating basic server and client repo
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd server
  $ mkcommit B0
  $ hg up 0
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ mkcommit C0
  created new head
  $ cd ../client
  $ hg pull
  pulling from $TESTTMP/A6/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files (+1 heads)
  new changesets d73caddc5533:0f88766e02d6 (2 drafts)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkcommit A1
  created new head
  $ hg up 'desc(C0)'
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ mkcommit B1
  $ hg debugobsolete `getid "desc(A0)" ` `getid "desc(A1)"`
  1 new obsolescence markers
  obsoleted 1 changesets
  1 new orphan changesets
  $ hg debugobsolete `getid "desc(B0)" ` `getid "desc(B1)"`
  1 new obsolescence markers
  obsoleted 1 changesets
  $ hg log -G --hidden
  @  d70a1f75a020 (draft): B1
  |
  | o  f6082bc4ffef (draft): A1
  | |
  o |  0f88766e02d6 (draft): C0
  |/
  | x  d73caddc5533 (draft): B0
  | |
  | x  8aaa48160adc (draft): A0
  |/
  o  1e4be0697311 (public): root
  

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

  $ hg push
  pushing to $TESTTMP/A6/server
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files (+1 heads)
  2 new obsolescence markers
  obsoleted 2 changesets

  $ cd ../..