fix: allow non-default ports to be sent to the server binary on Linux

Author: rivques

rlbot/utils/gateway.py

@@ -9,6 +9,7 @@
 
 from rlbot.interface import RLBOT_SERVER_PORT
 from rlbot.utils.logging import DEFAULT_LOGGER
+from rlbot.utils.os_detector import CURRENT_OS
 
 
 def find_main_executable_path(
@@ -72,7 +73,11 @@ def launch(
         )
 
     port = find_open_server_port()
-    args = [str(path), str(port)]
+
+    if CURRENT_OS == "Windows":
+        args = [str(path), str(port)]
+    else:
+        args = f"{path} {port}" # on Unix, when shell=True, args must be a string for flags to reach the executable
     DEFAULT_LOGGER.info("Launching RLBotServer with via %s", args)
 
     return subprocess.Popen(args, shell=True, cwd=directory), port