Fix tests for running tests in Copr
Three fixes are included.
- Workaround of asserting RPM's existence when building package in Copr.
- Workaround of translate i386 to i686 when building package in a i386 target
in Copr.
- Configure user.name and user.email in cloned repository in
commands/test_*.py. This was detected when building packages in Fedora Copr.
Signed-off-by: Chenxiong Qi <cqi@redhat.com>