do not reuse address on Windows

socketserver.ThreadingTCPServer.allow_reuse_address must be False on
Windows systems, else several servers might be started on the same
port, and unspecified behaviour will happen

Fixes: #4695
Change-Id: Ic9f193e23854f9cd3413ab6e664ca8029a7c9c76
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/30523
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Georg Brandl <g.brandl@fz-juelich.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

frappy/protocol/interface/tcp.py

@@ -27,6 +27,7 @@ import sys
 import threading
 import time
 import errno
+import os
 
 from frappy.datatypes import BoolType, StringType
 from frappy.errors import SECoPError
@@ -169,7 +170,9 @@ class TCPRequestHandler(socketserver.BaseRequestHandler):
 
 class TCPServer(socketserver.ThreadingTCPServer):
     daemon_threads = True
-    allow_reuse_address = True
+    # on windows, 'reuse_address' means that several servers might listen on
+    # the same port, on the other hand, a port is not blocked after closing
+    allow_reuse_address = os.name != 'nt'  # False on Windows systems
 
     # for cfg-editor
     configurables = {