Initial implementation of 'ignore-stdin' flag

[rogalski]

This feature is beneficial when running in automated environments
liek CI servers. Current heuristic fails in some conditions.
With this flag enabled we can simply always ignore stdin
and fall back to using target repo.

Closes #56

Needs further discussion, especially regarding actual naming of flag (maybe disregard_stdin would be better idea), test coverage and docs examples.

Feature itself is kind of "meh, boring" :) .

[rogalski]

@jorisroovers any comments?

[rogalski]

@jorisroovers bump :)

[jorisroovers]

Apologies for the delay, life get's in the way :-) I'll try to circle back faster on your reply.

This looks really good! Just a minor suggestion in the code wrt the flag precedence.

Re: flag name, I agree it might be a little confusing, especially for the most common use-case which is linting the local repo (without specifying the --target flag). In this case, the word 'target' is likely to trip users up.
Having said that, I spent a few min brainstorming (see below) and couldn't immediately think of a better name. If you don't know of anything else, then I'm good to move ahead with the suggested force-target-repo.

# target: might be confusing for most common use-case of reading repo in current working dir
force-target-repo
force-use-target

# local: implies we always read the local repo, even if a --target is specified (we don't want this)
force-local-repo

# git: doesn't sound right to me for some reason
force-git-repo
force-use-git-repo
force-read-git-repo

[jorisroovers]

Wondering whether it makes sense to make lint_config.force_target_repo the first option in the if block, like so:

    if lint_config.force_target_repo:
        LOG.debug("--force-target-repo flag specified. Reading from local repository.")
        gitcontext = GitContext.from_local_repository(lint_config.target, ctx.obj[2])
    elif msg_filename:
        LOG.debug("Attempting to read from --msg-filename.")
        gitcontext = GitContext.from_commit_msg(ustr(msg_filename.read()))
    elif stdin_input:
        LOG.debug("No --msg-filename flag. Using data passed via stdin.")
    else:
        # ...

Reasoning is that if a user uses a flag called '--force-xxx', I think they'd expect the force word to imply that it to take precedence over everything else (incl --msg-filename).

[rogalski]

Maybe just --ignore-stdin switch is better idea? In that case if statements do not have to be rearranged.

[jorisroovers]

That's a great idea! Much more intuitive CLI argument name too!
Would you mind updating the code (or submitting new PR, whatever is easier)?

[jorisroovers]

This is great, thank you!

I'll wrap a few other things over the next few days (max 1 week) and then push this out as part of the 0.12.0 release.

Thanks!