Make the FragmentMementoMgr return early if the string it's given has no length.
Make the FragmentMementoMgr return early if the string it's given has no length.

foam-framework/foam,osric-the-knight/foam,jacksonic/foam,jacksonic/foam,foam-framework/foam,foam-framework/foam,osric-the-knight/foam,mdittmer/foam,jlhughes/foam,mdittmer/foam,jlhughes/foam,jacksonic/foam,mdittmer/foam,mdittmer/foam,foam-framework/foam,jlhughes/foam,osric-the-knight/foam,osric-the-knight/foam,foam-framework/foam,jacksonic/foam,jlhughes/foam