Right now, runtests.py accepts only model names to test- this isn't grand if you're specifically after running a regressiontest however, or even django.contrib.*. One can use trial, but that requires setting up a few extra envvars- it's not hard to do, it's just a fair bit of a hit to the workflow (at least it is for me).
Attached is a patch mangling runtests.py so that it takes modeltests.model1, regressiontests.regresion1 args instead of just model names- additionally, can take modeltests.* or regressiontests.* to enable all tests for that namespace (basically). So for example-
python tests/runtests.py --settings=settings -v 1 basic
becomes
python tests/runtests.py --settings=settings -v 1 modeltests.basic
Upshot of that slightly larger invocation, is that regressiontests, django.contrib, any namespace can be specified now-
python tests/runtests.py --settings=settings -v 1 regressiontests.bug639
python tests/runtests.py --settings=settings -v 1 django.contrib.sessions