Running tests will multiple targets makes test.integ.process tests fail

Running run_tests.py with "-it RUN_OPEN,RUN_SOCKET" or "-it RUN_ALL" makes the test.integ.process tests fail.

test_launch_tor_with_config                                  [FAILURE]
test_launch_tor_with_timeout                                 [FAILURE]

======================================================================
ERROR: test_launch_tor_with_config
----------------------------------------------------------------------
Traceback:
  File "/home/neena/code/stem/test/integ/process.py", line 21, in setUp
    os.makedirs(DATA_DIRECTORY)
  File "/usr/lib/python2.7/os.py", line 157, in makedirs
    mkdir(name, mode)
OSError: [Errno 17] File exists: '/tmp/stem_integ'

======================================================================
ERROR: test_launch_tor_with_timeout
----------------------------------------------------------------------
Traceback:
  File "/home/neena/code/stem/test/integ/process.py", line 21, in setUp
    os.makedirs(DATA_DIRECTORY)
  File "/usr/lib/python2.7/os.py", line 157, in makedirs
    mkdir(name, mode)
OSError: [Errno 17] File exists: '/tmp/stem_integ'

----------------------------------------------------------------------
Ran 2 tests in 0.019s

FAILED

It looks like a problem with the test cleanup. I haven't really looked at the (related) code.