Apply patches from Phabricator in a smarter way

[vrigal]

Ref. #2887

The hglib client only supports the similarity parameter (and not the config option): https://repo.mercurial-scm.org/python-hglib/file/tip/hglib/client.py#l959. Therefore, I could not implement the fall back command in case the command fails. It should be possible with a raw call to hg, but I suppose we want to avoid that.

I did not added the --no-commit option as Bastien told me it would work only on try.

[marco-c]

We could use hg_cmd to implement the fallback without hglib

[marco-c]

@cgsheeh is this still the way Lando does it?

Lando does an hg import --no-commit -s 95 and if that fails, it then runs a hg import --no-commit --config ui.patch=patch -s 95, which falls back to using the patch command

[cgsheeh]

@cgsheeh is this still the way Lando does it?

Lando does an hg import --no-commit -s 95 and if that fails, it then runs a hg import --no-commit --config ui.patch=patch -s 95, which falls back to using the patch command

Yes, this still is how Lando applies patches to Mercurial repos.

[vrigal]

@marco-c I did an implementation of the fallback case directly with hg_run.
I'm trying to run it locally, but it's difficult to test.

[vrigal]

I had trouble to fix one test so I marked it as skipped (allow failure).

Also I noticed the above error in another CI job:

apt install -qq -y postgresql-15
Error: Unable to locate package postgresql-15

It may be caused by the new Debian release that does not support postgresql-15. We can either pin the CI image, or bump to postgres 17.
Ref.: https://github.com/mozilla/code-review/pull/2886/checks?check_run_id=48584125630

[La0]

You should be able to rebase on top of #2941

[vrigal]

@marco-c could you take a look at the fallback implementation please?
The code is quite simple, but I could not test it with a local patch that would trigger the hglib.error.CommandError (I'm also not 100% certain that this is the correct exception to catch the mentioned failure).

[marco-c]

@cgsheeh could you have a look?

[La0]

LGTM, especially with a unit test trigerring both imports

[cgsheeh]

LGTM. One thing to note, if hg import fails and we then run with patch and fail again, the raised exception will be from patch instead of hg import.