plv8 and pg_buildext

Hello,

I've recently been using pg_buildext to template control.in files, and
it's pretty great. However, I did run into this problem with plv8 and
its generated control file, with the practical consequence being that
it seems that the plv8 debian package cannot really support building
for several postgresql versions at the same time (at least, it
wouldn't when I submitted to a launchpad), being saved by
"supported-versions" *only* possessing 9.3 in current Debian/Trusty.

I did get around this by finding this helpful thread reporting the same bug:

http://lists.alioth.debian.org/pipermail/pkg-postgresql-public/2013-May/001197.html

I applied a workaround seen in that thread and copied a modified
pg_buildext (without srcdir=$srcdir) into "debian/" and it worked like
a charm, I think:

http://lists.alioth.debian.org/pipermail/pkg-postgresql-public/2013-May/001233.html

However, as evidenced by that response, it was somehow sub-ideal.

This workaround works for my own packages (I want plv8 for 9.2), but I
thought I'd re-raise that come 9.4 this may be a problem and caused
some grief in at least one instance.

Cheers.