remove unused imports
remove trailing whitespace
disable some pylint warnings
C: 68, 0: Unnecessary parens after not keyword (superfluous-parens)
C:321, 0: No space allowed after bracket
        packages = [ ts.dbMatch() ]
                   ^ (bad-whitespace)
C:321, 0: No space allowed before bracket
        packages = [ ts.dbMatch() ]
                                  ^ (bad-whitespace)
waive E:321,24: Instance of TransactionSet has no dbMatch member (no-member)
skip /var/lib/mock when --clean

otherwise we would be checking buildroots of mock
move pylint directives up
R:254, 0: Too many branches (15/12) (too-many-branches)
make pylint run mandatory
no dot generate reports
we don't need to use difflib to compare files

Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>