transaction: use the standard transaction mechanism to backup branch
Branch is a bit special :
- It currently does not collaborate with the transaction (or any scoping) for
writing (this is bad)
- It can change without the lock being taken (it is protected by `wlock`)
So we rely on the same mechanism as for the backup of the other dirstate file:
- we only do a backup if we hold the wlock
- we force a backup though the transaction
Since "branch" write does not collaborate with the transaction, we cannot back
it up "at the last minute" as we do for the dirstate. We have to back it up
"upfront". Since we have a backup, the transaction is no longer doing its
"quick_abort" and get noisy. Which is quite annoying. To work around this, and
to avoid jumping in yet-another-rabbit-hole of "getting branch written
properly", I am doing horrible things to the transaction in the meantime.
We should be able to get this code go away during the next cycle.
In the meantime, I prefer to take this small stop so that we stop abusing the
"journal" and "undo" mechanism instead of the proper backup mechanism of the
transaction.
Also note that this change regress the warning message for the legacy fallback
introduced in 2008 when
issue902 got fixed in
dd5a501cb97f (Mercurial 1.0).
I feel like this is fine as issue 902 remains fixed, and this would only affect
people deploying a mix of 15 year old Mercurial and modern mercurial, and using
branch and rollback extensively.
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.