Index: src/sites/all/modules/contrib/term_fields/term_fields.install
===================================================================
--- src/sites/all/modules/contrib/term_fields/term_fields.install	(revision 1391)
+++ src/sites/all/modules/contrib/term_fields/term_fields.install	(working copy)
@@ -94,3 +94,18 @@
 
   return $ret;
 }
+
+/**
+ * Alter {term_fields} primary key
+ */
+function term_fields_update_6101() {
+  $ret = array();
+
+  $sql = "ALTER TABLE {term_fields} DROP PRIMARY KEY";
+  $ret[] = update_sql($sql);
+
+  $sql = "ALTER TABLE {term_fields} ADD PRIMARY KEY (vid, fid)";
+  $ret[] = update_sql($sql);
+
+  return $ret;
+}