Tests fail with release tarballs

[aballier]

If I use e.g. rospkg-1.0.33.tar.gz:

$ tar xf rospkg-1.0.33.tar.gz
$ cd rospkg-1.0.33/
$ nosetests
....................................................................................F...........

FAIL: test.test_rospkg_packages.test_get_package_name

---

Traceback (most recent call last):
File "/usr/lib64/python2.7/site-packages/nose/case.py", line 197, in runTest
self.test(*self.arg)
File "/tmp/rospkg-1.0.33/test/test_rospkg_packages.py", line 295, in test_get_package_name
assert 'rospkg' == get_package_name(test_dir), get_package_name(test_dir)
AssertionError: rospkg-1.0.33

---

Ran 96 tests in 0.397s

FAILED (failures=1)

As far as I can tell the test is correct, however, the basedir being 'rospkg-1.0.33' confuses it: I've been sedding test/test_rospkg_packages.py to inject the version in the test but maybe there's a better solution.