In EAPI<3, ED and EROOT end up in the ebuild environment file and become "static". However, these are used as if they were D and ROOT, but they are not. D and ROOT (and ED and EROOT in EAPI3+) are generated dynamically depending on the current PORTAGE_TMPDIR and root directory parameter. On systems with different PORTAGE_TMPDIR, glibc binpkgs are completely broken due to this. Please fix the ebuild not to use a build time generated ED and EROOT, since this is not working as you think it is.
*** This bug has been marked as a duplicate of bug 473728 ***