The ZFS update to onnv_141 brought with it support for a
security label attribute called mlslabel. This feature
depends on zones to work correctly and while I originally
added minimal support for this in libspl that was a mistake.
Supporting this under Linux is not required and this is
just additional troublesome code to support. Long term
something like this could be supported under Linux but it
will need to be clearly thought through them an implemented.