Fixes #4600 The base is lost when changing plugin

include/class_listing.inc

@@ -1500,7 +1500,7 @@ class listing {
       }
     }
 
-    if (!isset($this->bases[$this->base])) {
+    if (!empty($this->bases) && !isset($this->bases[$this->base])) {
       $this->base = key($this->bases);
     }
 

include/simpleplugin/class_simpleManagement.inc

@@ -192,7 +192,7 @@ class simpleManagement extends management
 
     $this->configureHeadpage();
     $this->configureFilter();
-    if ($this->departmentBrowser === FALSE) {
+    if ($this->baseMode === FALSE) {
       $this->headpage->setBase($this->config->current['BASE']);
     }
   }