Please consider the error message:
[Error 32] The process cannot access the file because it is being used by another process: 'C:\buildslave\3.x.moore-windows\build\build\test_python_2284'
So there is still a process (most likely from a previous test run) that has one of the files open that would need to be deleted. Most likely, some popup window is displayed on the machine, and clicking it would terminate that process, allowing the files to be removed.
You have to get into contact with the slave admin and ask him to clean the buildbot before anything can proceed.