Otherwise, a lot of important tools (like even Xorg) are broken until all of them are rebuilt (that can take a long time on some machines) Thanks Reproducible: Always
preserve-libs is a portage feature that the end user has to set, so I don't know why you opened this bug. There isn't anything I can do to force users to turn that on.
Actually it is on by default.
I am referring to preserve_libs function from eutils.eclass (I am still running unmasked portage)
This is fixed in udev-187, thanks for the report.