repo-upgrade: write new requirement before upgrading the dirstate
This will prevent a small race condition where another hg process still
believes the repo is dirstate-v1 during the upgrade process.
This is good to have, but it is not a proper fix for the underlying problem.
There is code that assumes a requirement means a usage, e.g. having the
`generaldelta` requirement would imply *all* revlogs to use general delta,
but it's not true, it simply means that the repository advertises to the
client it needs to understand `generaldelta` in order to read the repo.
In the case of the dirstate, having the requirement *technically* should always
be the same as using dirstate-v2, since there is only one dirstate and
requirements should be as minimal as possible. However, we should not assume
this and make the code more robust in a future patch (series).
Mercurial
=========
Mercurial is a fast, easy to use, distributed revision control tool
for software developers.
Basic install::
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
Running without installing::
$ make local # build for inplace usage
$ ./hg --version # should show the latest version
See https://mercurial-scm.org/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.
Notes for packagers
===================
Mercurial ships a copy of the python-zstandard sources. This is used to
provide support for zstd compression and decompression functionality. The
module is not intended to be replaced by the plain python-zstandard nor
is it intended to use a system zstd library. Patches can result in hard
to diagnose errors and are explicitly discouraged as unsupported
configuration.