ENH: include explicit list of new files which should not be there upon "install --root"

that is to figure out what gets there on failing travis tests:

e.g. https://travis-ci.org/fail2ban/fail2ban/jobs/7112324
ENH: also print the failing traceback line in case of failure

Also to troubleshoot
https://travis-ci.org/fail2ban/fail2ban/jobs/7112324