Comment # 5 on bug 967772 from Dr. Werner Fink

Do you have solved the problem, e.g. by using nofail as described in
man:systemd.mount(5):

       If nofail is given, this mount will be only wanted, not required, by the
       local-fs.target. This means that the boot will continue even if this
       mount point is not mounted successfully. Option fail has the opposite
       meaning and is the default.