python3Packages.threat9-test-bed: fix missing async service loop

pkgs/development/python-modules/threat9-test-bed/asyncio-loop.patch

@@ -0,0 +1,18 @@
+diff --git a/threat9_test_bed/telnet_service/telnet_server.py b/threat9_test_bed/telnet_service/telnet_server.py
+index 7d29e8f..77f5e48 100644
+--- a/threat9_test_bed/telnet_service/telnet_server.py
++++ b/threat9_test_bed/telnet_service/telnet_server.py
+@@ -6,8 +6,11 @@ logger = logging.getLogger(__name__)
+ 
+ class TelnetServer:
+     def __init__(self, host: str, port: int, protocol):
+-        self.loop = asyncio.get_event_loop()
+-
++        try:
++            self.loop = asyncio.get_running_loop()
++        except RuntimeError:
++            self.loop = asyncio.new_event_loop()
++            asyncio.set_event_loop(self.loop)
+         coro = self.loop.create_server(protocol, host, port)
+         self.server = self.loop.run_until_complete(coro)
+ 

pkgs/development/python-modules/threat9-test-bed/default.nix

@@ -26,6 +26,8 @@ buildPythonPackage rec {
     hash = "sha256-0YSjMf2gDdrvkDaT77iwfCkiDDXKHnZyI8d7JmBSuCg=";
   };
 
+  patches = [ ./asyncio-loop.patch ];
+
   build-system = [ setuptools-scm ];
 
   dependencies = [