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.
$ mkdir test
$ cd test
$ echo foo>foo
$ hg init
$ hg addremove
adding foo
$ hg commit -m "1"
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
$ hg clone . ../branch
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd ../branch
$ hg co
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo bar>>foo
$ hg commit -m "2"
$ cd ../test
$ hg pull ../branch
pulling from ../branch
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
(run 'hg update' to get a working copy)
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 2 changesets, 2 total revisions
$ hg co
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cat foo
foo
bar
$ hg manifest --debug
6f4310b00b9a147241b071a60c28a650827fb03d 644 foo