As suggested by @kparal, this adds a test that specifies an
additional repository using a metalink. The repository contains
a single package, 'testpackage', that supplements glibc (so it
should always get installed). The test runs an install then
checks that testpackage got installed.
We also deduplicate a pair of needles which were matching on the
same anaconda UI feature (an "add" button) and use that same
needle in this test.
Signed-off-by: Adam Williamson <awilliam@redhat.com>
