I believe this test is causing the clang buildbot to hang. The trick to reproduce the failure is to run "make check" from build/tools/lldb/test. Note that this uses dosep.py to run the tests. In comparison, tools/lldb/test/dotest.py runs to completion. I'm not sure why Tuesday's commit started to hang consistently from Thursday night, but it could have something to do with the order in which tests are run now.
As "make check" runs to completion when I revert this commit, I'll commit that change to see how it pans out on the buildbots...