taxonomy_form_term_submit is not correctly set

After enabling the metatag module, I could not edit or delete any taxonomy term. The form appeared normally, but after submitting, the changes were not saved.

The taxonomy term edit form uses the default FAPI submit callback - but as soon as another module adds it's own submit handler, the default taxonomy_form_term_submit is never called. I think, the submit handler should be set as the taxonomy.module allows modules to put their fields in with field_attach_form('taxonomy_term', $term, $form, $form_state)

Sure, the contrib module causes the problem - but I think it would be wiser to put the solution in core. I add a patch file with my fast solution.