Comment # 3 on bug 66632 from Lauri Kasanen

No, I'm afraid you need git + patches to test.

You can build a local mesa and test it without installing, that way your system
is not at risk.

./configure --etc etc && make
export LD_LIBRARY_PATH=lib
export LIBGL_DRIVERS_PATH=lib/gallium
# now everything in this shell will use the new driver

glxinfo # check the output
xonotic --etc-etc