Process spawner - process group

This change will spawn the new subprocess task into its own process
group. It will give us more control over the signal handling since the
signals won't be propagated to the subprocess any more.

Signed-off-by: Jan Richter <jarichte@redhat.com>

Author: richtja

avocado/plugins/spawners/process.py

@@ -53,12 +53,16 @@ async def spawn_task(self, runtime_task):
 
         # pylint: disable=E1133
         try:
+            preexec_fn = None
+            if hasattr(os, "setpgrp"):
+                preexec_fn = os.setpgrp
             proc = await asyncio.create_subprocess_exec(
                 runner,
                 *args,
                 stdout=asyncio.subprocess.DEVNULL,
                 stderr=asyncio.subprocess.DEVNULL,
                 env=get_python_path_env_if_egg(),
+                preexec_fn=preexec_fn
             )
         except (FileNotFoundError, PermissionError):
             return False