Send stdout to devnull when checking nspawn known arg

We only need stderr, let's send any output printed to stdout
to /dev/null

diff --git a/mkosi/backend.py b/mkosi/backend.py
index 41d3cbb6bafda0d483bdf37034d95fabe64a72c3..b1debc2d28a205c63d8d3649d2d43ff3c9c5b4fe 100644 (file)
--- a/mkosi/backend.py
+++ b/mkosi/backend.py
@@ -654,7 +654,8 @@ def var_tmp(root: Path) -> Path:
 
 
 def nspawn_knows_arg(arg: str) -> bool:
-    return "unrecognized option" not in run([nspawn_executable(), arg], stderr=subprocess.PIPE, check=False, text=True).stderr
+    return "unrecognized option" not in run([nspawn_executable(), arg], stdout=subprocess.DEVNULL,
+                                            stderr=subprocess.PIPE, check=False, text=True).stderr
 
 
 def format_rlimit(rlimit: int) -> str: