Only unlock config if we did lock it

We only acquired a config lock if it was not shared in order
to have lock-free reads. Hence, only release the config lock
if we actually acquired it.
Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Niklas Hambuechen <niklash@google.com>

lib/config.py

@@ -2929,7 +2929,7 @@ class ConfigWriter(object):
       except Exception, err:
         logging.critical("Can't write the configuration: %s", str(err))
         raise
-    elif not self._offline:
+    elif not self._offline and not self._lock_current_shared:
       logging.debug("Unlocking configuration without writing")
       self._wconfd.UnlockConfig(self._GetWConfdContext())