Use StringIO.StringIO in Py2

Author: jnothman

numpydoc/tests/test_main.py

@@ -1,11 +1,14 @@
 from numpydoc.__main__ import main
 
 import sys
-import io
+try:
+    from StringIO import StringIO
+except ImportError:
+    from io import StringIO
 
 
 def test_main():
-    f = io.StringIO()
+    f = StringIO()
     sys.stdout, old_stdout = f, sys.stdout
     main(['numpydoc.__main__.main'])
     assert f.getvalue().strip() == main.__doc__