SHS cache system doesn't work correctly

drupal_static_reset should be only for taxonomy_get_tree.
Replaced drupal_static_reset() to drupal_static_reset('taxonomy_get_tree').

I'will try to remember what this patch do and explain in short:)

So, the original problems:

(1) Term that has been deleted is stored in a cache. Steps to reproduce:
- Create term "Tag A" and add it to a node;
- Remove term "Tag A".
- Edit node. Term is still present in a field.

In order to fix it we should reset static variable (taxonomy_get_tree) before shs_term_get_children() will be executed:

+  // Reset centrally stored static variables.
+  drupal_static_reset('taxonomy_get_tree');

It won't work, because shs_form_taxonomy_form_term_submit() is executed before the original submit taxonomy_form_term_submit(), so:

#10.2

-    array_unshift($form['#submit'], 'shs_form_taxonomy_form_term_submit');
+    $form['#submit'][] = 'shs_form_taxonomy_form_term_submit';

and this (#10.3) in order to rebuild the shs cache:

 function shs_form_taxonomy_form_term_submit(&$form, &$form_state) {
-  // Update vocabulary cache for the terms parents.
-  $parents = db_select('taxonomy_term_hierarchy', 'tth')
-          ->fields('tth', array('parent'))
-          ->condition('tid', $form_state['term']->tid)
-          ->execute()
-          ->fetchAll();
-  if ($parents) {
-    // Update vocabulary cache for the terms parents.
-    foreach ($parents as $parent) {
-      shs_term_get_children($form_state['term']->vid, $parent->parent, array('node_count' => TRUE), TRUE);
-    }
-  }
+  shs_term_get_children($form['#vocabulary']->vid, 0, array('node_count' => TRUE), TRUE);
 }

Why do you remove the logic of updating the terms parents here?
Try moving a term to a different point within the hierarchy and select one of its former parents within the widget ...

This won't break nothing. This is executed, after the confirmation of deleting taxonomy term.

Try moving a term to a different point within the hierarchy and select one of its former parents within the widget ...

This is related to shs_form_taxonomy_overview_terms_submit() and this is the second problem.

(2) Rebuilding the cache does not work correctly (if it concerns of taxonomy terms with parents).

The patch is fixed this problem (it doesn't work with original code).

About #10.1:
I didn't remember why I made this change. It seems you are right and it can cause a notice, if we will use "Reset to alphabetic". But from other side $form_state['complete form']['#vocabulary']->vid won't work for "Reset to alphabetic" too. This will avoid notices only.

So, I've prepared new patch, which corrects #10.1, it should work like a charm. I guess, I missed nothing:)

Why do you remove the logic of updating the terms parents here?
Try moving a term to a different point within the hierarchy and select one of its former parents within the widget ...

hmm, probably I don't understand something but it is executed after deletion of a taxonomy term (I mean this function shs_form_taxonomy_form_term_submit()). We can't do this "moving a term to a different point" here. This is a part of code where submit is added:

function shs_form_taxonomy_form_term_alter(&$form, &$form_state, $form_id) {
  if (isset($form_state['confirm_delete']) && isset($form_state['values']['vid'])) {
    // Add custom submit handler to update cache.
    $form['#submit'][] = 'shs_form_taxonomy_form_term_submit';
  }
}

If you edit a term and select a new parent for the term the cache for all parents within the hierarchy needs to be rebuild.

It works fine. I checked different ways. Try to apply patch;)
I don't think that there is some problems with cache:)