branchcache: use an explicit class for the v2 version
This prepare the introduction of an experimental v3 format version.
In the process, we move the description of the format in that new class.
$ cat <<EOF >> $HGRCPATH
> [extensions]
> hooklib =
>
> [phases]
> publish = False
> EOF
$ hg init a
$ hg --cwd a debugbuilddag '.:parent.:childa*parent/childa<parent@otherbranch./childa'
$ hg --cwd a log -G
o changeset: 4:a9fb040caedd
|\ branch: otherbranch
| | tag: tip
| | parent: 3:af739dfc49b4
| | parent: 1:66f7d451a68b
| | user: debugbuilddag
| | date: Thu Jan 01 00:00:04 1970 +0000
| | summary: r4
| |
| o changeset: 3:af739dfc49b4
| | branch: otherbranch
| | parent: 0:1ea73414a91b
| | user: debugbuilddag
| | date: Thu Jan 01 00:00:03 1970 +0000
| | summary: r3
| |
+---o changeset: 2:a6b287721c3b
| |/ parent: 0:1ea73414a91b
| | parent: 1:66f7d451a68b
| | user: debugbuilddag
| | date: Thu Jan 01 00:00:02 1970 +0000
| | summary: r2
| |
o | changeset: 1:66f7d451a68b
|/ tag: childa
| user: debugbuilddag
| date: Thu Jan 01 00:00:01 1970 +0000
| summary: r1
|
o changeset: 0:1ea73414a91b
tag: parent
user: debugbuilddag
date: Thu Jan 01 00:00:00 1970 +0000
summary: r0
$ hg init b
$ cat <<EOF >> b/.hg/hgrc
> [hooks]
> pretxnchangegroup.reject_merge_commits = \
> python:hgext.hooklib.reject_merge_commits.hook
> EOF
$ hg --cwd b pull ../a -r a6b287721c3b
pulling from ../a
adding changesets
adding manifests
adding file changes
error: pretxnchangegroup.reject_merge_commits hook failed: a6b287721c3b rejected as merge on the same branch. Please consider rebase.
transaction abort!
rollback completed
abort: a6b287721c3b rejected as merge on the same branch. Please consider rebase.
[255]
$ hg --cwd b pull ../a -r 1ea73414a91b
pulling from ../a
adding changesets
adding manifests
adding file changes
added 1 changesets with 0 changes to 0 files
new changesets 1ea73414a91b (1 drafts)
(run 'hg update' to get a working copy)
$ hg --cwd b pull ../a -r a9fb040caedd
pulling from ../a
searching for changes
adding changesets
adding manifests
adding file changes
added 3 changesets with 0 changes to 0 files
new changesets 66f7d451a68b:a9fb040caedd (3 drafts)
(run 'hg update' to get a working copy)