FreeBSD Try to set MAKE_JOBS_UNSAFE=yes and rebuild before

FreeBSD Try to set MAKE_JOBS_UNSAFE=yes and rebuild before，玛德，FreeBSD安装软件就是蛋疼~

mark

In some ports that failto build/upgrade, with portmaster in this case, I get a message like

gmake[1]: Leaving directory `/BETA1/usr/ports/multimedia/vlc/work9amd64/vlc-2.0.7'
gmake: *** [all] Error 2
===> Compilation failed unexpectedly.
Try to set MAKE_JOBS_UNSAFE=yes and rebuild before reporting the failure to
the maintainer.
*** [do-build] Error code 1

I also got this with mplayer and graphics/gstreamer-plugins-gl, resulting from the instructions in UPDATING 20130731.

I looked in man pages (portmaster, ports, make.conf, make) and online Porters' Handbook without finding anything.

So I want to know what MAKE_JOBS_UNSAFE=yes is supposed to do, and do I set it by

env MAKE_JOBS_UNSAFE=yes portmaster multimedia/vlc