Handle FileNotFoundError caused by processing new file in progressive mode

[kostyaplis]

Fixes #2363

[kostyaplis]

Apparently this breaks the desired behaviour when passing a non-existent file to ansible-lint.
Maybe we should be more specific that we are checking the old revision right now, so only in this case we can swallow FileNotFoundError.
E.g.

1. Add in_previous_revision=False to options Namespace
2. Set it to True when entering with _previous_revision() and set back to False before exiting
3. check if getattr(options, "in_previous_revision", False): in _populate_content_cache_from_disk(), then swallow FileNotFoundError

Does this sound reasonable?

[ssbarnea]

If I understood correctly, you were using progressive mode while still passing filenames as arguments to the linter. TBH, I never considered this use-case as most of the time we call it without even passing any file arguments.

[ssbarnea]

I personally do not like this hack because it is inside load content, I wonder if we could catch this error in a different place and ignore it.

Do you happen to have a repository where running linter in progressive can reproduce the bug? If so, I may be able to find a better place to catch this error and to ignore it.

[kostyaplis]

Yes, you can found test repository here
Run ansible-lint --progressive playbook-test1.yml to reproduce an error.

If I understood correctly, you were using progressive mode while still passing filenames as arguments to the linter. TBH, I never considered this use-case as most of the time we call it without even passing any file arguments.

Our repository contains >400 playbooks and >300 roles, so our idea is to only lint changed/added files and only report regressions(at least for now). That's why all the recent activity around progressive mode, as I'm actively testing it with our use-cases.

[ssbarnea]

It seems to be working but because no test was added, we might see it again in the future. Thanks!