Need to poll() to make sure we get the return code

Signed-off-by: Stefan Marr <git@stefan-marr.de>

Author: smarr

rebench/subprocess_with_timeout.py

@@ -106,6 +106,7 @@ def process_output(self, proc):
                     reads.append(proc.stderr.fileno())
 
                 if not reads:
+                    proc.poll()
                     break
 
                 ret = select(reads, [], [], 0.1)