checkheads: upgrade the obsolescence postprocessing logic (issue4354)
The previous logic had many shortcoming (eg: looking at the head only, not
handling prune, etc...), the new logic use a more robust approach:
For each head, we check if after the push all changesets exclusive to this heads
will be obsolete. If they are, the branch considered be "replaced".
To check if a changeset will be obsolete, we simply checks:
* the changeset phase
* the existence of a marker relevant to the "pushed set" that affects the
changesets..
This fixes two major issues of the previous algorithm:
* branch partially rewritten (eg: head but not root) are no longer detected as
replaced,
* Prune are now properly handled.
(This implementation was introduction in the evolve extension, version 6.0.0.)
This new algorithm has an extended number of tests, a basic one is provided
in this patch. The others will be introduced in their own changeset for clarity.
In addition, we stop trying to process heads unknown locally, we do not have
enough data to take an informed decision so we should stop pretending we do.
This reflect a test that is now update.
running: init test1
result: None
running: add foo
result: 0
running: commit -m commit1 -d 2000-01-01 foo
result: None
running: commit -m commit2 -d 2000-01-02 foo
result: None
running: log -r 0
changeset: 0:0e4634943879
user: test
date: Sat Jan 01 00:00:00 2000 +0000
summary: commit1
result: None
running: log -r tip
changeset: 1:45589e459b2e
tag: tip
user: test
date: Sun Jan 02 00:00:00 2000 +0000
summary: commit2
result: None