Make sure workunit task does not create mnt.N by itself.
Make sure workunit task does not create mnt.N by itself.

This used to hide a bug in the rbd task, where rbd
created the mountpoint with the wrong name. The workunits
ended up running against the local filesystem.

ktdreyer/teuthology,zhouyuan/teuthology,ktdreyer/teuthology,dmick/teuthology,yghannam/teuthology,michaelsevilla/teuthology,t-miyamae/teuthology,ceph/teuthology,robbat2/teuthology,zhouyuan/teuthology,SUSE/teuthology,dmick/teuthology,michaelsevilla/teuthology,tchaikov/teuthology,SUSE/teuthology,dreamhost/teuthology,ivotron/teuthology,caibo2014/teuthology,ivotron/teuthology,ceph/teuthology,dmick/teuthology,robbat2/teuthology,SUSE/teuthology,yghannam/teuthology,dreamhost/teuthology,caibo2014/teuthology,t-miyamae/teuthology,tchaikov/teuthology