py3: Handle 'StringIO' to 'io' transition.

This isn't so much a rename as a migration, since things don't do the
same thing.

Based on patch by: Stephen Finucane <stephen@that.guru>

git-svn-id: http://svn.code.sf.net/p/docutils/code/trunk@8368 929543f6-e4f2-0310-98a6-ba3bd3dd1d04

3 files changed, 18 insertions, 3 deletions

diff --git a/docutils/docutils/writers/docutils_xml.py b/docutils/docutils/writers/docutils_xml.py
index 16eb03898..8113c0b98 100644
--- a/docutils/docutils/writers/docutils_xml.py
+++ b/docutils/docutils/writers/docutils_xml.py
@@ -12,12 +12,17 @@ __docformat__ = 'reStructuredText'
 
 import sys
 import xml.sax.saxutils
-from StringIO import StringIO
 
 import docutils
 from docutils import frontend, writers, nodes
 
 if sys.version_info >= (3, 0):
+    from io import StringIO  # noqa
+else:
+    from StringIO import StringIO  # noqa
+
+
+if sys.version_info >= (3, 0):
     unicode = str  # noqa
 
 
diff --git a/docutils/test/test_utils.py b/docutils/test/test_utils.py
index e5036bc7b..0f53355eb 100755
--- a/docutils/test/test_utils.py
+++ b/docutils/test/test_utils.py
@@ -9,12 +9,17 @@
 Test module for utils/__init__.py.
 """
 
-from io import StringIO
 import os
+import sys
 import unittest
 
 from DocutilsTestSupport import docutils, utils, nodes
 
+if sys.version_info >= (3, 0):
+    from io import StringIO
+else:
+    from StringIO import StringIO
+
 
 class ReporterTests(unittest.TestCase):
 
diff --git a/docutils/test/test_writers/test_docutils_xml.py b/docutils/test/test_writers/test_docutils_xml.py
index c39523dae..abab5742a 100755
--- a/docutils/test/test_writers/test_docutils_xml.py
+++ b/docutils/test/test_writers/test_docutils_xml.py
@@ -15,12 +15,17 @@ Test for docutils XML writer.
 """
 from __future__ import absolute_import
 
-from StringIO import StringIO
+import sys
 
 from . import DocutilsTestSupport # must be imported before docutils
 import docutils
 import docutils.core
 
+if sys.version_info >= (3, 0):
+    from io import StringIO
+else:
+    from StringIO import StringIO
+
 # sample strings
 # --------------