server: fix systemd variable scope

Change 31280 introduced an error where an import was overridden, which
leads python to consider it a local variable, preventing access to the
systemd import. (TODO: a better way to handle the systemd import?)

Fixes: #4732
Change-Id: I5188a8737392bd8befcdfa9af044a21be9af908a
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/31386
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Alexander Zaft <a.zaft@fz-juelich.de>

frappy/server.py

@@ -130,14 +130,15 @@ class Server:
         pass
 
     def run(self):
+        global systemd  # pylint: disable=global-statement
         while self._restart:
             self._restart = False
             try:
                 # TODO: make systemd notifications configurable
-                if systemd:  # pylint: disable=used-before-assignment
+                if systemd:
                     systemd.daemon.notify("STATUS=initializing")
             except Exception:
-                systemd = None  # pylint: disable=redefined-outer-name
+                systemd = None
             try:
                 self._processCfg()
                 if self._testonly: