Use asyncio.ensure_future() instead of asyncio.async() with conservative approach to support Python < 3.4.4. Fixes https://github.com/GNS3/gns3-gui/issues/2566

gns3server/compute/docker/docker_vm.py

@@ -29,6 +29,7 @@ import os
 from gns3server.utils.asyncio.telnet_server import AsyncioTelnetServer
 from gns3server.utils.asyncio.raw_command_server import AsyncioRawCommandServer
 from gns3server.utils.asyncio import wait_for_file_creation
+from gns3server.utils.asyncio import asyncio_ensure_future
 from gns3server.utils.get_resource import get_resource
 
 from gns3server.ubridge.ubridge_error import UbridgeError, UbridgeNamespaceError
@@ -567,7 +568,7 @@ class DockerVM(BaseNode):
 
         output_stream.feed_data(self.name.encode() + b" console is now available... Press RETURN to get started.\r\n")
 
-        asyncio.async(self._read_console_output(self._console_websocket, output_stream))
+        asyncio_ensure_future(self._read_console_output(self._console_websocket, output_stream))
 
     @asyncio.coroutine
     def _read_console_output(self, ws, out):