Clone master branch of roottest if matching remote branch doesn't exist
Clone master branch of roottest if matching remote branch doesn't exist

Fixes: ROOT-9708

karies/root,root-mirror/root,olifre/root,olifre/root,root-mirror/root,olifre/root,root-mirror/root,olifre/root,root-mirror/root,olifre/root,karies/root,root-mirror/root,olifre/root,karies/root,olifre/root,olifre/root,olifre/root,root-mirror/root,karies/root,karies/root,root-mirror/root,root-mirror/root,root-mirror/root,karies/root,olifre/root,karies/root,karies/root,root-mirror/root,root-mirror/root,karies/root,karies/root,karies/root,olifre/root