The xorg-x11-6.8.0-r2 ebuild has DEPEND="opengl? ( >=x11-base/opengl-update-1.99 )" and RDEPEND=">=x11-base/opengl-update-1.7.2" This is causing portage to try and pull in opengl-update-2.0_pre1 as a dependency of xorg-x11, but opengl-update-2.0_pre1 is masked by package.mask and so the emerge fails. Reproducible: Always Steps to Reproduce: 1. 2. 3.
but xorg-x11-6.8.0-r2 is in package.mask, too...
So it is, sorry about that, I forgot I unmasked it. That still doesn't explain how I was able to install it the first time round, since opengl-update is not unmasked.
Because the dependencies changed, as things do in hard-masked ebuilds. =)