md5sum.py uses at least 1 undefined object in Python 3.4.1. I only tried this on Windows. I have no idea if it is a problem on any other OS.

C:\>C:\Python27\python.exe --version
Python 2.7.6

C:\>C:\Python34\python.exe --version
Python 3.4.1

C:\>C:\Python34\python.exe C:\Python34\Tools\Scripts\md5sum.py C:\Python34\python.exe
Traceback (most recent call last):
  File "C:\Python34\Tools\Scripts\md5sum.py", line 90, in <module>
    sys.exit(main(sys.argv[1:], sys.stdout))
  File "C:\Python34\Tools\Scripts\md5sum.py", line 87, in main
    return sum(args, out)
  File "C:\Python34\Tools\Scripts\md5sum.py", line 27, in sum
    if files and isinstance(files[-1], file):
NameError: name 'file' is not defined

Here is why . . .

C:\>C:\Python27\python.exe -c "print(file)"
<type 'file'>

C:\>C:\Python34\python.exe -c "print(file)"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
NameError: name 'file' is not defined

So "file" is defined in 2.7.6 but not in 3.4.1.

I guess it's only the evidence that it isn't being used.

Well, at least one person *tried* to use it :)

This is not a windows only problem, I can reproduce it on linux. Obviously we don't have tests for this tool.

Here's a path with tests.

Hmmm, I was just reloading the page to post a patch I'd worked up, and lo and behold there's already one here! Here's mine anyway; you can use any parts of it that you like, Berker. There are a couple of not-quite-related changes in test_tools that might be better split into a separate issue, but they're in there anyway.

Thanks Zachary! Here's a combined patch.

Thanks for the patch, Zachary.

New changeset eafe4007c999 by Berker Peksag in branch '3.4':
Issue bpo-21906: Make Tools/scripts/md5sum.py work in Python 3.
http://hg.python.org/cpython/rev/eafe4007c999

New changeset e1913d2780d7 by Berker Peksag in branch 'default':
Issue bpo-21906: Merge from 3.4.
http://hg.python.org/cpython/rev/e1913d2780d7