Use six to portably handle module renames in Python 2 and 3

llvm-svn: 250915
diff --git a/lldb/test/api/multiple-debuggers/TestMultipleDebuggers.py b/lldb/test/api/multiple-debuggers/TestMultipleDebuggers.py
index 1064e37..369a6b1 100644
--- a/lldb/test/api/multiple-debuggers/TestMultipleDebuggers.py
+++ b/lldb/test/api/multiple-debuggers/TestMultipleDebuggers.py
@@ -1,6 +1,8 @@
 """Test the lldb public C++ api when doing multiple debug sessions simultaneously."""
 
-import os, re, StringIO
+import lldb_shared
+
+import os, re
 import unittest2
 from lldbtest import *
 import lldbutil