Reset the branch state due to improper import.
RHEL git ref that the branch was reset to
<31f1df52f72ef741c148f1a711b29c2d2d51c1d6>.
Summary:
* `.gitignore`
Loosen the matching rules.
* `dead.package.c9s`
This file is irrelevant for C8S/RHEL 8.
Related: rhbz#2149262