Fix util script to work when TRAVIS_BRANCH is unset.
Fix util script to work when TRAVIS_BRANCH is unset.

pieis2pi/Slic3r,alexrj/Slic3r,curieos/Slic3r,pieis2pi/Slic3r,pieis2pi/Slic3r,pieis2pi/Slic3r,alexrj/Slic3r,alexrj/Slic3r,alexrj/Slic3r,pieis2pi/Slic3r,alexrj/Slic3r,curieos/Slic3r,curieos/Slic3r,pieis2pi/Slic3r,curieos/Slic3r,alexrj/Slic3r,curieos/Slic3r,curieos/Slic3r