processes: better handling of PID that are not part of RhodeCode processes.

- in some cases for multiple gunicorn instances the PID sent is not from rhodecode which
would lead to AccessDenied errors. We prevent from crashing the server on this type of errors.

rhodecode/apps/admin/views/process_management.py

@@ -105,9 +105,10 b' class AdminProcessManagementView(BaseApp'
     def process_management_signal(self):
         pids = self.request.json.get('pids', [])
         result = []
+
         def on_terminate(proc):
             msg = "process `PID:{}` terminated with exit code {}".format(
-                proc.pid, proc.returncode)
+                proc.pid, proc.returncode or 0)
             result.append(msg)
 
         procs = []
@@ -121,15 +122,22 b' class AdminProcessManagementView(BaseApp'
 
                 children = proc.children(recursive=True)
                 if children:
-                    print('Wont kill Master Process')
+                    log.warning('Wont kill Master Process')
                 else:
                     procs.append(proc)
 
         for p in procs:
-            p.terminate()
+            try:
+                p.terminate()
+            except psutil.AccessDenied as e:
+                log.warning('Access denied: {}'.format(e))
+
         gone, alive = psutil.wait_procs(procs, timeout=10, callback=on_terminate)
         for p in alive:
-            p.kill()
+            try:
+                p.kill()
+            except psutil.AccessDenied as e:
+                log.warning('Access denied: {}'.format(e))
 
         return {'result': result}