Retry starting shadow copy if it failes due to a SNAPSHOP_SET_IN_PROGRESS error
Retry starting shadow copy if it failes due to a SNAPSHOP_SET_IN_PROGRESS error

uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend