Fix setuptools.sandbox._execfile() with Python 3.1.

It fixes failure of setuptools.tests.test_sandbox.TestSandbox.test_setup_py_with_CRLF() with Python 3.1.

setuptools/sandbox.py

@@ -34,12 +34,12 @@ def _execfile(filename, globals, locals=None):
     Python 3 implementation of execfile.
     """
     mode = 'rb'
-    # Python 2.6 compile requires LF for newlines, so use deprecated
-    #  Universal newlines support.
-    if sys.version_info < (2, 7):
-        mode += 'U'
     with open(filename, mode) as stream:
         script = stream.read()
+    # compile() function in Python 2.6 and 3.1 requires LF line endings.
+    if sys.version_info[:2] < (2, 7) or sys.version_info[:2] >= (3, 0) and sys.version_info[:2] < (3, 2):
+        script = script.replace(b'\r\n', b'\n')
+        script = script.replace(b'\r', b'\n')
     if locals is None:
         locals = globals
     code = compile(script, filename, 'exec')