tests: Fix check-packagekit failure without any /etc/pki/product/*
tests: Fix check-packagekit failure without any /etc/pki/product/*

This is the case on RHEL 7.5 beta.

Reviewed-by: Peter <a316049dd34607c62d4611d63ab22a6454add223@redhat.com>

martinpitt/cockpit,andreasn/cockpit,mareklibra/cockpit,stefwalter/cockpit,mareklibra/cockpit,cockpituous/cockpit,petervo/cockpit,SotolitoLabs/cockpit,mvollmer/cockpit,petervo/cockpit,mareklibra/cockpit,deryni/cockpit,stefwalter/cockpit,SotolitoLabs/cockpit,moraleslazaro/cockpit,Scribery/cockpit,Scribery/cockpit,SotolitoLabs/cockpit,Scribery/cockpit,mareklibra/cockpit,stefwalter/cockpit,andreasn/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,deryni/cockpit,mareklibra/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,stefwalter/cockpit,cockpit-project/cockpit,martinpitt/cockpit,mvollmer/cockpit,SotolitoLabs/cockpit,garrett/cockpit,martinpitt/cockpit,cockpituous/cockpit,cockpituous/cockpit,deryni/cockpit,andreasn/cockpit,Scribery/cockpit,deryni/cockpit,SotolitoLabs/cockpit,garrett/cockpit,Scribery/cockpit,Scribery/cockpit,andreasn/cockpit,petervo/cockpit,cockpit-project/cockpit,Scribery/cockpit,mareklibra/cockpit,garrett/cockpit,cockpit-project/cockpit,andreasn/cockpit,stefwalter/cockpit,cockpit-project/cockpit,petervo/cockpit,andreasn/cockpit,mvollmer/cockpit,SotolitoLabs/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,mvollmer/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,SotolitoLabs/cockpit,deryni/cockpit,deryni/cockpit,deryni/cockpit,moraleslazaro/cockpit,mareklibra/cockpit,stefwalter/cockpit,martinpitt/cockpit,mvollmer/cockpit,petervo/cockpit,andreasn/cockpit,cockpituous/cockpit,petervo/cockpit,stefwalter/cockpit,garrett/cockpit,garrett/cockpit,petervo/cockpit