Comment 2 for bug 1646064

I do not believe glibc is at fault here.

I've been test building ubiquity. It builds in zesty, and it builds in zesty-proposed, with all packages from zesty proposed but: libgl1-mesa-glx libglapi-mesa.

Let me try with libgl1-mesa-glx libglapi-mesa from zesty-proposed, but glibc from zesty-release, to conclusively exclude glibc. And that fails, downgrading those two mesa packages still resolves everything. Therefore I am certain that current glibc in zesty-proposed is good, and it is the mesa that is now borked / at fault with Xvfb. See bug #1647600 for mesa. https://bugs.launchpad.net/ubuntu/+source/mesa/+bug/1647600