skip test_not_writable_ipdir if I can't create a non-writable dir

such as when running as root

just came across this running iptest in a docker container. This was the only test that failed.

IPython/utils/tests/test_path.py

@@ -14,6 +14,7 b' from contextlib import contextmanager'
 
 from os.path import join, abspath, split
 
+from nose import SkipTest
 import nose.tools as nt
 
 from nose import with_setup
@@ -471,6 +472,14 b' def test_not_writable_ipdir():'
     ipdir = os.path.join(tmpdir, '.ipython')
     os.mkdir(ipdir)
     os.chmod(ipdir, 600)
+    try:
+        os.listdir(ipdir)
+    except OSError:
+        pass
+    else:
+        # I can still read an unreadable dir,
+        # assume I'm root and skip the test
+        raise SkipTest("I can't create directories that I can't list")
     with AssertPrints('is not a writable location', channel='stderr'):
         ipdir = path.get_ipython_dir()
     env.pop('IPYTHON_DIR', None)