Revert "Don't add local branch refspec if remote branch is empty. Integration tests needed."

This reverts commit 95a37bdbe2f3a0826b6092caaef16dcaa8ddca0a.

Git pull failed when try pull from local branch from non tracked remote with this changes
Merge branch 'release/2.47'
Merge remote-tracking branch 'gitextensions/master' into BuildServerIntegration