documentation: add some internals documentation about bid merge
This is an important algorithm that was only documented on the wiki so far.
Some update to the algorithm (and associated doc) is to expected in the future
since the bid merge algorithm is bug-ridden when it comes to file deletion comes
to play.
Differential Revision: https://phab.mercurial-scm.org/D8711
$ echo '[extensions]' >> $HGRCPATH
$ echo 'strip =' >> $HGRCPATH
$ cat >findbranch.py <<EOF
> from __future__ import absolute_import
> import re
> import sys
>
> head_re = re.compile(r'^#(?:(?:\\s+([A-Za-z][A-Za-z0-9_]*)(?:\\s.*)?)|(?:\\s*))$')
>
> for line in sys.stdin:
> hmatch = head_re.match(line)
> if not hmatch:
> sys.exit(1)
> if hmatch.group(1) == 'Branch':
> sys.exit(0)
> sys.exit(1)
> EOF
$ hg init a
$ cd a
$ echo "Rev 1" >rev
$ hg add rev
$ hg commit -m "No branch."
$ hg branch abranch
marked working directory as branch abranch
(branches are permanent and global, did you want a bookmark?)
$ echo "Rev 2" >rev
$ hg commit -m "With branch."
$ hg export 0 > ../r0.patch
$ hg export 1 > ../r1.patch
$ cd ..
$ if "$PYTHON" findbranch.py < r0.patch; then
> echo "Export of default branch revision has Branch header" 1>&2
> exit 1
> fi
$ if "$PYTHON" findbranch.py < r1.patch; then
> : # Do nothing
> else
> echo "Export of branch revision is missing Branch header" 1>&2
> exit 1
> fi
Make sure import still works with branch information in patches.
$ hg init b
$ cd b
$ hg import ../r0.patch
applying ../r0.patch
$ hg import ../r1.patch
applying ../r1.patch
$ cd ..
$ hg init c
$ cd c
$ hg import --exact --no-commit ../r0.patch
applying ../r0.patch
warning: can't check exact import with --no-commit
$ hg st
A rev
$ hg revert -a
forgetting rev
$ rm rev
$ hg import --exact ../r0.patch
applying ../r0.patch
$ hg import --exact ../r1.patch
applying ../r1.patch
Test --exact and patch header separators (issue3356)
$ hg strip --no-backup .
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
>>> import re
>>> p = open('../r1.patch', 'rb').read()
>>> p = re.sub(br'Parent\s+', b'Parent ', p)
>>> open('../r1-ws.patch', 'wb').write(p) and None
$ hg import --exact ../r1-ws.patch
applying ../r1-ws.patch
$ cd ..