mq: factor out push conditions checks
Some extensions (e.g. hgsubversion) completely override push command. Because
extensions load order is unspecified, if hgsubversion loads before mq, mq
checks about not pushing applied patches will be bypassed. Short of finding a
way to fix load order, extracting the checking logic will allow
hgsubversion-like extensions to run the check themselves.
$ hg init repo
$ cd repo
$ hg init subrepo
$ echo a > subrepo/a
$ hg -R subrepo ci -Am adda
adding a
$ echo 'subrepo = subrepo' > .hgsub
$ hg ci -Am addsubrepo
adding .hgsub
committing subrepository subrepo
$ echo b > subrepo/b
$ hg -R subrepo ci -Am addb
adding b
$ hg ci -m updatedsub
committing subrepository subrepo
delete .hgsub and revert it
$ rm .hgsub
$ hg revert .hgsub
warning: subrepo spec file .hgsub not found
delete .hgsubstate and revert it
$ rm .hgsubstate
$ hg revert .hgsubstate
delete .hgsub and update
$ rm .hgsub
$ hg up 0
warning: subrepo spec file .hgsub not found
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg st
! .hgsub
$ ls subrepo
a
delete .hgsubstate and update
$ hg up -C
warning: subrepo spec file .hgsub not found
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm .hgsubstate
$ hg up 0
remote changed .hgsubstate which local deleted
use (c)hanged version or leave (d)eleted? c
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg st
$ ls subrepo
a