Do not honor `.slugignore`

[schneems]

Had a customer who had their entire test directory ignored by .slugignore and the directory was silently deleting it. I imagine more people have done this.

At bare minimum we should be outputting something like what we see in build

-----> Deleting 2 files matching .slugignore patterns.

I think though that since these slugs are not intended to live as long (and boot up time is slightly important) that we ignore the .slugignore.

If we decide that it's not acceptable to ignore .slugignore than we'll need to create a new paradigm for ignoring files in production, but not in test. Something like .slugignore-except-in-test.

[gudmundur]

@schneems Oh nice catch. Given how .slugignore is processed before any of the CI code is executed during build, I'm not sure can address this now. We've been talking about folding parts of the CI build into the build system, at that point we're in a better spot to figure this out. For the time being the workaround is to leave the test directory out of the .slugignore.

[schneems]

If we cannot change the behavior I would at least like to see an output of the contents of .slugignore otherwise it takes about half a day to request a user push to a support branch, just so we can download it and check to see if there is a .slugignore file (versus simply checking the CI output`.

[piwii]

I lost 2 hours of my life when I tried heroku CI because test directory was in slugignore 👎

[adiakritos]

I lost a whole day and a half searching for a reason my /spec directory was being deleted.