Python 2 seems to be acting up when I try to import certbot.util in those files. Python 3 is fine with it. In the filesystem.py case, it seems to be some kind of circular import issue (certbot.util imports certbot._internal.lock, which imports certbot.compat.filesystem, which tries to import certbot.util). Not sure what http_01.py is doing. I'll take another look at it.

====================================================== ERRORS ======================================================
__________________________________ ERROR collecting certbot/tests/account_test.py __________________________________
ImportError while importing test module '/home/silvio/Documents/python/certbot/certbot/tests/account_test.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
certbot/tests/account_test.py:15: in <module>
    from certbot.compat import filesystem
certbot/certbot/compat/filesystem.py:9: in <module>
    from certbot import util
certbot/certbot/util.py:25: in <module>
    from certbot._internal import lock
certbot/certbot/_internal/lock.py:7: in <module>
    from certbot.compat import filesystem
E   ImportError: cannot import name filesystem

To fix the Travis failures, you need to update this line to certbot>=1.6.0.dev0 and this line to -e certbot[dev].

Whats going on here is the tests are trying to run certbot-apache with the oldest version of certbot it claims to support which is currently version 1.1.0, but this version doesn't have certbot.util.os_umask being added in this PR. Updating the minimum required version should solve this problem.

Documenting how all this works is tracked by #7647.

@bmw are you saying we add in that change to that line to the pull request even though it might affect things beyond #8020?

I'm not entirely sure what you have in mind when you say it might affect things beyond this PR, but yes, I think the changes I described should be made in this PR. This PR is making our Apache plugin require the latest version of Certbot which I think is the best approach, but tests will fail until the Apache plugin's dependencies are updated to state this.