[gentoo-dev] Broken ebuilds

[P.C.]

Hi,

I've been trying to set up a Gentoo system using an older version of
the portage tree [1]. Most of it goes well, but some ebuilds stopped
merging correctly. Namely, it's Python 2.7. While merging, it
requests the following file:
http://gentoo.ussg.indiana.edu/distfiles/python-gentoo-patches-2.7.3-1.tar.bz2
which is a 404, therefore forcing me to install Python manually.

Is that "ebuild decay" intentional? How long I can expect ebuilds to
stay useful?

Before someone suggests I should upgrade to current snapshot - my use
case depends on pkgcore which doesn't support newer portage tree.

Is this broken ebuild a bug?

Cheers,
P.C.

[1] Portage tree from 2013-02-07
http://git.calculate.ru/?p=calculate/portage.git;a=snapshot;h=65adf3c525b50d70792d5c89814a17a7712447fc;sf=tgz