test: Write nicer error message when triggering non-existing pull requests
test: Write nicer error message when triggering non-existing pull requests

Closes #3711

Reviewed-by: Dominik Perpeet <f7830b2723a5db4fc185058b06cfab4b89a38da9@redhat.com>

arilivigni/cockpit,stefwalter/cockpit,michalskrivanek/cockpit,Scribery/cockpit,dperpeet/cockpit,jscotka/cockpit,dperpeet/cockpit,xhad/cockpit,dperpeet/cockpit,andreasn/cockpit,petervo/cockpit,vanloswang/cockpit,larsu/cockpit,stefwalter/cockpit,larsu/cockpit,vanloswang/cockpit,mareklibra/cockpit,xhad/cockpit,mareklibra/cockpit,deryni/cockpit,cockpituous/cockpit,deryni/cockpit,stefwalter/cockpit,sgallagher/cockpit,matobet/cockpit,jscotka/cockpit,mareklibra/cockpit,harishanand95/cockpit,deryni/cockpit,moraleslazaro/cockpit,deryni/cockpit,martinpitt/cockpit,sgallagher/cockpit,arilivigni/cockpit,matobet/cockpit,sgallagher/cockpit,xhad/cockpit,petervo/cockpit,mareklibra/cockpit,larsu/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,vanloswang/cockpit,michalskrivanek/cockpit,larskarlitski/cockpit,cockpit-project/cockpit,Scribery/cockpit,jscotka/cockpit,vanloswang/cockpit,vanloswang/cockpit,cockpit-project/cockpit,xhad/cockpit,larskarlitski/cockpit,mareklibra/cockpit,petervo/cockpit,matobet/cockpit,martinpitt/cockpit,matobet/cockpit,larskarlitski/cockpit,larsu/cockpit,sgallagher/cockpit,mvollmer/cockpit,arilivigni/cockpit,arilivigni/cockpit,dperpeet/cockpit,arilivigni/cockpit,garrett/cockpit,garrett/cockpit,stefwalter/cockpit,petervo/cockpit,michalskrivanek/cockpit,andreasn/cockpit,arilivigni/cockpit,deryni/cockpit,dperpeet/cockpit,larskarlitski/cockpit,cockpit-project/cockpit,xhad/cockpit,SotolitoLabs/cockpit,harishanand95/cockpit,larsu/cockpit,larskarlitski/cockpit,andreasn/cockpit,Scribery/cockpit,martinpitt/cockpit,harishanand95/cockpit,Scribery/cockpit,cockpit-project/cockpit,harishanand95/cockpit,garrett/cockpit,michalskrivanek/cockpit,harishanand95/cockpit,cockpit-project/cockpit,SotolitoLabs/cockpit,mvollmer/cockpit,sgallagher/cockpit,sgallagher/cockpit,garrett/cockpit,vanloswang/cockpit,moraleslazaro/cockpit,SotolitoLabs/cockpit,deryni/cockpit,dperpeet/cockpit,jscotka/cockpit,stefwalter/cockpit,mvollmer/cockpit,mareklibra/cockpit,michalskrivanek/cockpit,SotolitoLabs/cockpit,harishanand95/cockpit,cockpituous/cockpit,Scribery/cockpit,matobet/cockpit,garrett/cockpit,moraleslazaro/cockpit,SotolitoLabs/cockpit,petervo/cockpit,moraleslazaro/cockpit,andreasn/cockpit,jscotka/cockpit,michalskrivanek/cockpit,stefwalter/cockpit,cockpituous/cockpit,cockpituous/cockpit,cockpituous/cockpit,andreasn/cockpit,petervo/cockpit,andreasn/cockpit,martinpitt/cockpit,michalskrivanek/cockpit,vanloswang/cockpit,mvollmer/cockpit,SotolitoLabs/cockpit,cockpituous/cockpit,Scribery/cockpit,larsu/cockpit,larskarlitski/cockpit,harishanand95/cockpit,moraleslazaro/cockpit,dperpeet/cockpit,xhad/cockpit,arilivigni/cockpit,moraleslazaro/cockpit,matobet/cockpit,stefwalter/cockpit,martinpitt/cockpit,petervo/cockpit,SotolitoLabs/cockpit,andreasn/cockpit,jscotka/cockpit,larskarlitski/cockpit,xhad/cockpit,mareklibra/cockpit,sgallagher/cockpit,Scribery/cockpit,deryni/cockpit