When testing if a variant has some modules,
it's no longer enough to look at `variant.modules`. That attribute
contains only names of modules configured in variants.xml.
With modules being specified in `pkgset_koji_module_builds` or
`pkgset_scratch_modules` options it is possible the code wouldn't
trigger even if there was a module.
JIRA: RHELCMP-3054
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>