diff --git a/runbot/runbot.py b/runbot/runbot.py
index 7516022b..77dcd4e9 100644
--- a/runbot/runbot.py
+++ b/runbot/runbot.py
@@ -548,7 +548,7 @@ class runbot_build(osv.osv):
 
         return cmd, mods
 
-    def spawn(self, cmd, lock_path, log_path, cpu_limit=None, shell=False):
+    def spawn(self, cmd, lock_path, log_path, cpu_limit=None, shell=False, hidestderr=False):
         def preexec_fn():
             os.setsid()
             if cpu_limit:
@@ -562,7 +562,11 @@ class runbot_build(osv.osv):
             lock(lock_path)
         out=open(log_path,"w")
         _logger.debug("spawn: %s stdout: %s", ' '.join(cmd), log_path)
-        p=subprocess.Popen(cmd, stdout=out, stderr=out, preexec_fn=preexec_fn, shell=shell)
+        if hidestderr:
+            stderr = out
+        else:
+            stderr = open(os.devnull, 'w')
+        p=subprocess.Popen(cmd, stdout=out, stderr=stderr, preexec_fn=preexec_fn, shell=shell)
         return p.pid
 
     def github_status(self, cr, uid, ids, context=None):