largefiles: introduce "_lfcommithooks" to abstract pre-committing procedures
This changes allows to customize pre-committing procedures according
to conditions.
This patch uses "stack" with an element instead of flag like
"_isXXXXing" or so, because:
- the former works correctly even when customizations are nested, and
- ensuring at least one element can ignore empty check
http://mercurial.selenic.com/bts/issue842
$ hg init
$ echo foo > a
$ hg ci -Ama
adding a
$ hg up -r0000
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo bar > a
Should issue new head warning:
$ hg ci -Amb
adding a
created new head
$ hg up -r0000
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo stuffy > a
Should not issue new head warning:
$ hg ci -q -Amc
$ hg up -r0000
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo crap > a
$ hg branch testing
marked working directory as branch testing
(branches are permanent and global, did you want a bookmark?)
Should not issue warning:
$ hg ci -q -Amd