sepolicy/generate.py: Fix string formatting

Fixes python3 problem:

>>> print("Failed to retrieve rpm info for %s") % package
Failed to retrieve rpm info for %s
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for %: 'NoneType' and 'str'

Signed-off-by: Petr Lautrbach <plautrba@redhat.com>
1 file changed