Created attachment 360276 [details, diff] Patch to the -r28 ebuild According to the devmanual (see URL), that's where it should be done. Suggest patching -r28 in place, leaving the stable ebuilds alone.
Ok, in light of bug #217042, disregard this. The users are created for convenience and not needed at compile time. Hitting Ctrl-C after the user creation but before src_compile does indeed leave a user on your system, not desired at all.