Clean up sys.path entry.

IPython/lib/tests/test_deepreload.py

@@ -11,6 +11,7 b' import sys'
 import nose.tools as nt
 
 from IPython.testing import decorators as dec
+from IPython.utils.syspathcontext import prepended_to_syspath
 from IPython.utils.tempdir import TemporaryDirectory
 from IPython.lib.deepreload import reload as dreload
 
@@ -33,7 +34,7 b' def test_deepreload_numpy():'
 def test_deepreload():
     "Test that dreload does deep reloads and skips excluded modules."
     with TemporaryDirectory() as tmpdir:
-        sys.path.insert(0, tmpdir)
+        with prepended_to_syspath(tmpdir):
         with open(os.path.join(tmpdir, 'A.py'), 'w') as f:
             f.write("class Object(object):\n    pass\n")
         with open(os.path.join(tmpdir, 'B.py'), 'w') as f: