[MERGE][Win32] explicit close of file in textfile

[Aaron Bentley]

John Arbash Meinel wrote:
>>This patch fixes the binary file detection by explicitly closing the
>>file, which is needed on win32.
> +1 from me. Though I honestly believe that CPython will have closed the
> file either by the time text_file is done, or by the time
> check_text_path is done.
> 
> If you are seeing otherwise, I would be interested to hear about it.

I have seen otherwise.  On win32, the test_contents_merge2 test fails 
with EPERM unless you do this.  Of course, then it fails because diff3 
doesn't handle line endings properly, but...

Aaron