State of support for back PG branches

I had originally been planning to back-port this fix:
http://archives.postgresql.org/pgsql-committers/2005-08/msg00213.php
as far as 7.2.  I've completed the back-port as far as 7.3, but found
that 7.2 would be significantly more work because the API of
heap_fetch() would need to change from what it was back then, and the
patch would therefore have to touch many places that it does not touch
in later versions.  Given that the bug is so low-probability that it's
escaped detection all this time, it doesn't really seem worth the effort
(not to mention risk of creating new bugs).

This brings up the question of whether we should officially abandon
support for 7.2 and/or later branches.  I don't think anyone is planning
on supporting old branches forever, but when do we stop?

I have a corporate need to keep supporting 7.3, at least to the extent
of critical bug fixes, because Red Hat is still on the hook to support
that version in RHEL3 for awhile longer.  I have no such interest in
7.2 (which is one reason I'm not excited about doing the extra work to
back-patch the VACUUM/ctid fix).  I can definitely see that the
community might not want to expend more effort on 7.3, though.  I have
no idea what the needs of other distributions might be.

Thoughts anyone?
        regards, tom lane