#79732 by drewish, fix the taxonomy forms and some code cleanup.

modules/taxonomy/taxonomy.module

@@ -75,7 +75,8 @@ function taxonomy_menu($may_cache) {
 
     $items[] = array('path' => 'admin/content/taxonomy/add/vocabulary',
       'title' => t('add vocabulary'),
-      'callback' => 'taxonomy_admin_vocabulary_edit',
+      'callback' => 'drupal_get_form',
+      'callback arguments' => array('taxonomy_form_vocabulary'),
       'access' => user_access('administer taxonomy'),
       'type' => MENU_LOCAL_TASK);
 
@@ -105,22 +106,23 @@ function taxonomy_menu($may_cache) {
   }
   else {
     if (is_numeric(arg(3))) {
-      $items[] = array('path' => 'admin/content/taxonomy/' . arg(3),
+      $vid = arg(3);
+      $items[] = array('path' => 'admin/content/taxonomy/'. $vid,
         'title' => t('list terms'),
         'callback' => 'taxonomy_overview_terms',
-        'callback arguments' => array(arg(3)),
+        'callback arguments' => array($vid),
         'access' => user_access('administer taxonomy'),
         'type' => MENU_CALLBACK);
 
-      $items[] = array('path' => 'admin/content/taxonomy/' . arg(3) . '/list',
+      $items[] = array('path' => 'admin/content/taxonomy/'. $vid .'/list',
         'title' => t('list'),
         'type' => MENU_DEFAULT_LOCAL_TASK,
         'weight' => -10);
 
-      $items[] = array('path' => 'admin/content/taxonomy/' . arg(3) . '/add/term',
+      $items[] = array('path' => 'admin/content/taxonomy/'. $vid .'/add/term',
         'title' => t('add term'),
-        'callback' => 'taxonomy_form_term',
-        'callback arguments' => array(array('vid' => arg(3))),
+        'callback' => 'drupal_get_form',
+        'callback arguments' => array('taxonomy_form_term', $vid),
         'access' => user_access('administer taxonomy'),
         'type' => MENU_LOCAL_TASK);
     }
@@ -165,6 +167,9 @@ function taxonomy_overview_terms($vid) {
 
   $header = array(t('Name'), t('Operations'));
   $vocabulary = taxonomy_get_vocabulary($vid);
+  if (!$vocabulary) {
+    return drupal_not_found();
+  }
 
   drupal_set_title(check_plain($vocabulary->name));
   $start_from      = $_GET['page'] ? $_GET['page'] : 0;
@@ -336,7 +341,8 @@ function taxonomy_vocabulary_confirm_delete($vid) {
   return confirm_form($form,
                   t('Are you sure you want to delete the vocabulary %title?',
                   array('%title' => $vocabulary->name)),
-                  'admin/content/taxonomy', t('Deleting a vocabulary will delete all the terms in it. This action cannot be undone.'),
+                  'admin/content/taxonomy',
+                  t('Deleting a vocabulary will delete all the terms in it. This action cannot be undone.'),
                   t('Delete'),
                   t('Cancel'));
 }
@@ -347,8 +353,7 @@ function taxonomy_vocabulary_confirm_delete_submit($form_id, $form_values) {
   return 'admin/content/taxonomy';
 }
 
-function taxonomy_form_term($edit = array()) {
-  $vocabulary_id = isset($edit['vid']) ? $edit['vid'] : arg(4);
+function taxonomy_form_term($vocabulary_id, $edit = array()) {
   $vocabulary = taxonomy_get_vocabulary($vocabulary_id);
 
   $form['name'] = array('#type' => 'textfield', '#title' => t('Term name'), '#default_value' => $edit['name'], '#maxlength' => 64, '#description' => t('The name for this term. Example: "Linux".'), '#required' => TRUE);
@@ -1276,29 +1281,29 @@ function taxonomy_term_page($str_tids = '', $depth = 0, $op = 'page') {
 }
 
 /**
- * Page to add or edit a vocabulary
+ * Page to edit a vocabulary
  */
 function taxonomy_admin_vocabulary_edit($vid = NULL) {
   if ($_POST['op'] == t('Delete') || $_POST['edit']['confirm']) {
-    return taxonomy_vocabulary_confirm_delete($vid);
+    return drupal_get_form('taxonomy_vocabulary_confirm_delete', $vid);
   }
-  elseif ($vid) {
-    $vocabulary = (array)taxonomy_get_vocabulary($vid);
+  if ($vocabulary = (array)taxonomy_get_vocabulary($vid)) {
+    return drupal_get_form('taxonomy_form_vocabulary', $vocabulary);
   }
-  return drupal_get_form('taxonomy_form_vocabulary', $vocabulary);
+  return drupal_not_found();
 }
 
 /**
- * Page to list terms for a vocabulary
+ * Page to edit a vocabulary term
  */
-function taxonomy_admin_term_edit($tid = NULL) {
+function taxonomy_admin_term_edit($tid) {
   if ($_POST['op'] == t('Delete') || $_POST['edit']['confirm']) {
-    return taxonomy_term_confirm_delete($tid);
+    return drupal_get_form('taxonomy_term_confirm_delete', $tid);
   }
-  elseif ($tid) {
-    $term = (array)taxonomy_get_term($tid);
+  if ($term = (array)taxonomy_get_term($tid)) {
+    return drupal_get_form('taxonomy_form_term', $term->vid, $term);
   }
-  return taxonomy_form_term($term);
+  return drupal_not_found();
 }
 
 /**