(In reply to roland@rptd.ch from comment #4)
> I tried compiling from source but it does not work. Seems to have troubles
> with libdrm.
> 
> configure: error: Package requirements (libdrm >= 2.4.75 libdrm_intel >=
> 2.4.75) were not met:
> 
> Can't seem to get past this one.

You must be building with more things enabled than your system Mesa is built
with.

Run

> ebuild /path/to/mesa-19.0.8.ebuild configure clean

and copy the line that it uses to configure with meson. Use that in your build
that you're using to bisect.

Alternatively, add "intel" to your VIDEO_CARDS setting and rebuild libdrm.