oeqa/runtime/rpm: ensure no user process running before deleting user

In case of systemd, `su -c 'xxx' test1' via ssh will create
several processes owned by test1, e.g. /lib/system/systemd --user.

These processes are actually managed by user@UID.service
(e.g. user@1000.service). And such service is managed
automatically by systemd. In other words, it will be cleaned
up by systemd automatically.

So we need to wait for systemd to clean it up before trying to
use `userdel' to delete the user.

(From OE-Core rev: 9d398be42a69d25277b929d760aaed1679f3cd54)

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/runtime/cases/rpm.py

@@ -4,6 +4,7 @@
 
 import os
 import fnmatch
+import time
 
 from oeqa.runtime.case import OERuntimeTestCase
 from oeqa.core.decorator.depends import OETestDepends
@@ -77,7 +78,21 @@ class RpmInstallRemoveTest(OERuntimeTestCase):
             msg = 'status: %s. Cannot run rpm -qa: %s' % (status, output)
             self.assertEqual(status, 0, msg=msg)
 
+        def check_no_process_for_user(u):
+            _, output = self.target.run(self.tc.target_cmds['ps'])
+            if u + ' ' in output:
+                return False
+            else:
+                return True
+
         def unset_up_test_user(u):
+            # ensure no test1 process in running
+            timeout = time.time() + 30
+            while time.time() < timeout:
+                if check_no_process_for_user(u):
+                    break
+                else:
+                    time.sleep(1)
             status, output = self.target.run('userdel -r %s' % u)
             msg = 'Failed to erase user: %s' % output
             self.assertTrue(status == 0, msg=msg)