Tests: ExternalProject DownloadServer.py left hanging
The code here added by !5034 (merged) blocks forever waiting for a connection. If for some reason the calling test is terminated, that connection is never made. Since the process was daemonized, it is not killed along with the rest of the test. The process is left hanging. On Windows, this locks the working directory and prevents it from being removed until the leftover python process is manually killed.