revset: use delayregistrar to register predicate in extension easily
Previous patch introduced 'revset.predicate' decorator to register
revset predicate function easily.
But it shouldn't be used in extension directly, because it registers
specified function immediately. Registration itself can't be restored,
even if extension loading fails after that.
Therefore, registration should be delayed until 'uisetup()' or so.
This patch uses 'extpredicate' decorator derived from 'delayregistrar'
to register predicate in extension easily.
This patch also tests whether 'registrar.delayregistrar' avoids
function registration if 'setup()' isn't invoked on it, because
'extpredicate' is the first user of it.
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