Restore primary key when saving over an existing revision

drupal_7_taxonomy_revision_1_4_existing_revision_primary_key.patch

diff --git a/taxonomy_revision.module b/taxonomy_revision.module
index ea72297..4ca3018 100644
--- a/taxonomy_revision.module
+++ b/taxonomy_revision.module
@@ -315,7 +315,7 @@ function _taxonomy_revision_taxonomy_term_save_revision($term) {
 
   // Save over an existing revision if requested.
   if (isset($term->revision_id) && $term->revision_id && empty($term->revision)) {
-    drupal_write_record('taxonomy_term_data_revision', $term);
+    drupal_write_record('taxonomy_term_data_revision', $term, array('revision_id'));
   }
   // Otherwise force a new revision to be created, and update the
   // {taxonomy_term_data} table with the new revision ID.