moonraker: attempt to resolve "event loop closed" errors on restart

Occasionally a server restart will fail as the new loop instantiates as closed.  This seems to be an issue with asyncio, attempt to work around by retyring to create a new loop.

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>

moonraker/moonraker.py

@@ -845,7 +845,18 @@ def main() -> None:
         # it is ok to use a blocking sleep here
         time.sleep(.5)
         logging.info("Attempting Server Restart...")
-        asyncio.set_event_loop(asyncio.new_event_loop())
+        for _ in range(5):
+            # Sometimes the new loop does not properly instantiate.
+            # Give 5 attempts before raising an exception
+            new_loop = asyncio.new_event_loop()
+            if not new_loop.is_closed():
+                break
+            logging.info("Failed to create open eventloop, "
+                         "retyring in .5 seconds...")
+            time.sleep(.5)
+        else:
+            raise RuntimeError("Unable to create new open eventloop")
+        asyncio.set_event_loop(new_loop)
         event_loop = EventLoop()
     event_loop.close()
     logging.info("Server Shutdown")