The build step above not only builds the packages but also unpacks all of them into subdirectories so that you can run the test suite against the packaged goods. This is intended to catch packaging problems such as not adding a new module to the packaging MANIFEST list(s). The runtest.py script supports a -p option and arguments that run the SCons tests against the different unpacked directories.
Edit the script to include the tests you want to include. If you want to be complete, test all of the packages.
To be quicker but still reasonably thorough, test tar-gz and zip, one each of local- and src- (probably do -tar-gz for one and -zip for the other), and rpm.
For a quick-n-dirty test, just test tar-gz or zip, and maybe rpm. Since all of the different packages use the same lists as input, it's pretty unlikely that the tests will pass on one package and fail for another.