Here's a patch using the '.tmp' suffix.
I also updated test_import.
Note that the current test_import.test_execute_bit_not_copied is a no-op:
"""
                fname = TESTFN + os.extsep + "py"
                create_empty_file(fname)
                os.chmod(fname, (stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH |
                                 stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH))
                __import__(TESTFN)
                fn = imp.cache_from_source(fname)
                if not os.path.exists(fn):
                    self.fail("__import__ did not result in creation of "
                              "either a .pyc or .pyo file")
                    s = os.stat(fn)
                    self.assertEqual(
                        stat.S_IMODE(s.st_mode),
                        stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH)

"""

The indentation is wrong: the stat() is never performed...
I'll fix that in 3.2 and 2.7.