1) prevents a bug by logging stdout/stderr if retcode still None:

```
in executeCmd
    if retcode < 0:
TypeError: unorderable types: NoneType() < int()
```
2) prevents a rarely test case bug of testExecuteTimeoutWithNastyChildren, because no stdout (Resource temporarily unavailable), possible no flush by IO of the killing process;

fail2ban/server/utils.py

@@ -159,7 +159,7 @@ class Utils():
 			# if was timeouted (killed/terminated) - to prevent waiting, set std handles to non-blocking mode.
 			if popen.stdout:
 				try:
-					if retcode < 0:
+					if retcode is None or retcode < 0:
 						Utils.setFBlockMode(popen.stdout, False)
 					stdout = popen.stdout.read()
 				except IOError as e:
@@ -169,7 +169,7 @@ class Utils():
 				popen.stdout.close()
 			if popen.stderr:
 				try:
-					if retcode < 0:
+					if retcode is None or retcode < 0:
 						Utils.setFBlockMode(popen.stderr, False)
 					stderr = popen.stderr.read()
 				except IOError as e:

fail2ban/tests/actiontestcase.py

@@ -247,7 +247,7 @@ class CommandActionTest(LogCaptureTestCase):
 		cpid = getnastypid()
 		# Verify that the process itself got killed
 		self.assertTrue(Utils.wait_for(lambda: not pid_exists(cpid), 3))  # process should have been killed
-		self.assertLogged('my pid ')
+		self.assertLogged('my pid ', 'Resource temporarily unavailable')
 		self.assertLogged('timed out')
 		self.assertLogged('killed with SIGTERM', 
 		                  'killed with SIGKILL')
@@ -261,7 +261,7 @@ class CommandActionTest(LogCaptureTestCase):
 		cpid = getnastypid()
 		# Verify that the process itself got killed
 		self.assertTrue(Utils.wait_for(lambda: not pid_exists(cpid), 3))
-		self.assertLogged('my pid ')
+		self.assertLogged('my pid ', 'Resource temporarily unavailable')
 		self.assertLogged('timed out')
 		self.assertLogged('killed with SIGTERM', 
 		                  'killed with SIGKILL')