By the way, this discussion brings up another problem. I wasn't able to write a test for this (to address the below concerns) because the test suite for thread-naming supplies some sort of auto-generated subject for threads with empty subjects. So we can't test behavior for dealing with empty subjects.
Unfortunately, I don't know the history of the test suite, or why this auto-subject decisicion was made, so I don't feel comfortable just changing the behavior.
