[BusyBox] double square bracket version of test in ash?

[Dan Kegel]

ltp.sf.net's test suite annoyingly uses about 300 lines of the form
./commands/cpio/cpio_tests.sh:  if [[ -z $LTPTMP && -z $TMPBASE ]]
even though [[ is not defined by Posix sh.

Is there a way of enabling [[ in ash, or should
I slog through and fix those 300 non-posixisms in ltp?
- Dan

-- 
Dan Kegel
http://www.kegel.com
http://counter.li.org/cgi-bin/runscript/display-person.cgi?user=78045