illumos.sh env file's LOCKNAME definition is busted
export LOCKNAME="$(basename -- "$CODEMGR_WS")_nightly.lock"
causes LOCKNAME to be equal to "--_nightly.lock" which causes all nightly runs to try to create the same lock file /tmp/--_nightly.lock. While this is ok on a single-user system that never runs multiple unreleated nightlys, it is only a matter of time before multi-user systems run into this problem. (It gets really annoying if you have an automated system like Jenkins locking out everyone from doing a nightly for hours on end.)
This used to work and the commit for bug 450 introduced the regression.