While working through the set of packages we will be likely to install
with SL 3.0.4 I spotted that we had pulled in tetex-1.0.7 (etc), which
we don't want (since we use a tetex-2.0.2 based tex but not installed
as an rpm).

It appears that following the chain of dependencies that we pulled it
in because of a2ps which (in SL 3.0.4 RC2 at least) has a dependency
on tetex-afm.

Previous builds of a2ps on RH8/9 (and FC1 etc) don't have this
dependency, and it isn't explicit in the a2ps SPEC file.  It seems
that the dependency is (automatically) added if rpmbuild is run on a
system which happens to have tetex-afm installed.

Should a2ps actually have this extra dependency?  Does it in RHEL?

Rebuilding a2ps on a system without tetex-afm installed produces an
rpm which doesn't have the extra dependency.  This might mean that one
should really only build packages on systems with the "minimum" set of
packages installed (those specified as BuildRequires in the SPEC file)
though I know from experience that this isn't in practise possible
(since many basic dependencies are missed in there).

When SL rpms are (re-)built does it happen in a special environment?
If so how is the set of available packages in the build environment
handled?

 -- Jon