Implement ability to exclude config files through the HAB_CONFIG_EXCLUDE variable

[efyang]

This implements the HAB_CONFIG_EXCLUDE variable, as discussed in #1120, which goes by the format of ",,,...", and provides a few reasonable defaults.

[thesentinels]

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[adamhjk]

Hey - we're getting some eyeballs on this, @efyang - thanks for contributing.

[adamhjk]

I think @fnichol needs to give this a once over, as he's got the 💯 bash skills.

My only comment is that the defaults might be overly broad.

[adamhjk]

I think .sw is too broad as a default, given that it will match anything with an .sw* extension. If we're trying to match .swp and .swap, I would rather we be explicit about it.

[smith]

Vim will use .swp, and if that doesn't exist try .swo, and move backward through the alphabet. I've heard of people using .sw?, but according to http://vimdoc.sourceforge.net/htmldoc/recover.html#recovery, if it needs to, it will keep going through the alphabet in reverse until .saa is reached. 🍭

For other programs, I have this feature turned off in vim, and ignore .sw? in my global gitignore and spare individual programs from having to worry about my specific editor settings.

[fnichol]

Would an alternative to a set default be no set default? This would allow users of their editor to tweak for themselves. I'd tend to agree with @adamhjk here (it feels too broad), however in this specific case (filtering entries under the config/ directory) I'm more okay with the chances of false positives.

It might make more sense to take @smith's suggestion and change *.sw* to .sw?.

[juliandunn]

@smith's suggestion seems good. If you have more than 20 temp files for your vim in one directory you're probably doing something wrong 😁

[efyang]

Swapped out *.sw* with *.sw?.

[fnichol]

Thanks @efyang, looking good!

OP fixed it

[chefsalim]

@thesentinels approve

[thesentinels]

🤘 I am testing your branch against master before merging it. We do this to ensure that the master branch is never failing tests.

[thesentinels]

Travis CI has started testing this PR.

[thesentinels]

💖 Travis CI reports this PR passed.

It always makes me feel nice when humans approve of one anothers work. I'm merging this PR now.

I just want you and the contributor to answer me one question: