Use --timestamp in placeholders if given

[twilligon]

Fixes #5189. {now} and {utcnow} will take the value of --timestamp if given. I also added a test for this functionality.

[ThomasWaldmann]

Looks good. Some questions:

• is location the only thing using the placeholders? maybe check which callers of replace_placeholders are relevant.
• what tzoffset does your test system have?

[ThomasWaldmann]

Also: can you please rebase on current master and push -f, so that the CI via github workflows kicks in?

[twilligon]

Location and some tests are the only things using replace_placeholders, aside from this part in remote.py:

borg/src/borg/remote.py

Lines 687 to 689 in 47e96bc

	remote_path = args.remote_path or os.environ.get('BORG_REMOTE_PATH', 'borg')
	remote_path = replace_placeholders(remote_path)
	return env_vars + [remote_path, 'serve'] + opts

I'm not sure if getting the value from --timestamp makes sense here; I don't think so.

My system has tzoffset -08:00 but that shouldn't matter as all the times involved are UTC. I tried changing my system's timezone and rerunning the tests, everything worked the same.

[ThomasWaldmann]

Thanks! Would you like to do a backport to 1.1-maint, so it gets into next 1.1.x release?

[ThomasWaldmann]

https://github.com/borgbackup/borg/pull/5472/checks?check_run_id=1349770343

hmm, can we find out why ubuntu / py37 is hanging?

[twilligon]

Sure, I'll backport.

[twilligon]

I can't reproduce the py37 hang on my local machine, although I'm not running Ubuntu. But the 1.1 backport passed CI just fine.