internals: document bundle2 format
It seems like a good idea to have thorough documentation of the bundle2
data format, including the format of each part and the capabilities.
The added documentation is far from complete. For example, we don't
fully capture the semantics of each capability and part. But a start
is better than nothing, which was pretty much where we were before.
Differential Revision: https://phab.mercurial-scm.org/D2298
$ hg init t
$ cd t
$ echo a > a
$ hg add a
$ hg commit -m test
$ rm .hg/requires
$ hg tip
abort: unknown version (2) in revlog 00changelog.i!
[255]
$ echo indoor-pool > .hg/requires
$ hg tip
abort: repository requires features unknown to this Mercurial: indoor-pool!
(see https://mercurial-scm.org/wiki/MissingRequirement for more information)
[255]
$ echo outdoor-pool >> .hg/requires
$ hg tip
abort: repository requires features unknown to this Mercurial: indoor-pool outdoor-pool!
(see https://mercurial-scm.org/wiki/MissingRequirement for more information)
[255]
$ cd ..
Test checking between features supported locally and ones required in
another repository of push/pull/clone on localhost:
$ mkdir supported-locally
$ cd supported-locally
$ hg init supported
$ echo a > supported/a
$ hg -R supported commit -Am '#0 at supported'
adding a
$ echo 'featuresetup-test' >> supported/.hg/requires
$ cat > $TESTTMP/supported-locally/supportlocally.py <<EOF
> from __future__ import absolute_import
> from mercurial import extensions, localrepo
> def featuresetup(ui, supported):
> for name, module in extensions.extensions(ui):
> if __name__ == module.__name__:
> # support specific feature locally
> supported |= {'featuresetup-test'}
> return
> def uisetup(ui):
> localrepo.localrepository.featuresetupfuncs.add(featuresetup)
> EOF
$ cat > supported/.hg/hgrc <<EOF
> [extensions]
> # enable extension locally
> supportlocally = $TESTTMP/supported-locally/supportlocally.py
> EOF
$ hg -R supported status
$ hg init push-dst
$ hg -R supported push push-dst
pushing to push-dst
abort: required features are not supported in the destination: featuresetup-test
[255]
$ hg init pull-src
$ hg -R pull-src pull supported
pulling from supported
abort: required features are not supported in the destination: featuresetup-test
[255]
$ hg clone supported clone-dst
abort: repository requires features unknown to this Mercurial: featuresetup-test!
(see https://mercurial-scm.org/wiki/MissingRequirement for more information)
[255]
$ hg clone --pull supported clone-dst
abort: required features are not supported in the destination: featuresetup-test
[255]
$ cd ..