Make test output for upstream remote conditional

If someone doesn't have a remote tracking wbsoft/frescobaldi.git
one can't test for it.
Fix upstream lookup

When looking for the remote that is tracking the official repo
I relied on 'wbsoft/frescobaldi.git' to be present.
Obviously 'wbsoft/frescobaldi' is enough.
Merge pull request #227 from uliska/fix-test

Fix lookup of 'upstream' remote