don't use private TestCase._exc_info() method in parametric test

In Python 2.6, the method is one line, returning sys.exc_info(), and has been removed in Python 2.7.

IPython/testing/_paramtestpy2.py

@@ -1,96 +1,97 b''
 """Implementation of the parametric test support for Python 2.x
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2009-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
+import sys
 import unittest
 from compiler.consts import CO_GENERATOR
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
 def isgenerator(func):
     try:
         return func.func_code.co_flags & CO_GENERATOR != 0
     except AttributeError:
         return False
 
 class ParametricTestCase(unittest.TestCase):
     """Write parametric tests in normal unittest testcase form.
 
     Limitations: the last iteration misses printing out a newline when running
     in verbose mode.
     """
     def run_parametric(self, result, testMethod):
         # But if we have a test generator, we iterate it ourselves
         testgen = testMethod()
         while True:
             try:
                 # Initialize test
                 result.startTest(self)
 
                 # SetUp
                 try:
                     self.setUp()
                 except KeyboardInterrupt:
                     raise
                 except:
-                    result.addError(self, self._exc_info())
+                    result.addError(self, sys.exc_info())
                     return
                 # Test execution
                 ok = False
                 try:
                     testgen.next()
                     ok = True
                 except StopIteration:
                     # We stop the loop
                     break
                 except self.failureException:
-                    result.addFailure(self, self._exc_info())
+                    result.addFailure(self, sys.exc_info())
                 except KeyboardInterrupt:
                     raise
                 except:
-                    result.addError(self, self._exc_info())
+                    result.addError(self, sys.exc_info())
                 # TearDown
                 try:
                     self.tearDown()
                 except KeyboardInterrupt:
                     raise
                 except:
-                    result.addError(self, self._exc_info())
+                    result.addError(self, sys.exc_info())
                     ok = False
                 if ok: result.addSuccess(self)
 
             finally:
                 result.stopTest(self)
 
     def run(self, result=None):
         if result is None:
             result = self.defaultTestResult()
         testMethod = getattr(self, self._testMethodName)
         # For normal tests, we just call the base class and return that
         if isgenerator(testMethod):
             return self.run_parametric(result, testMethod)
         else:
             return super(ParametricTestCase, self).run(result)
 
 
 def parametric(func):
     """Decorator to make a simple function into a normal test via unittest."""
 
     class Tester(ParametricTestCase):
         test = staticmethod(func)
 
     Tester.__name__ = func.__name__
 
     return Tester