addresses #973

reintroduce change that saves memcpy when primary key is covering index,
will add note to release notes stating not to have prefix as part of primary key

git-svn-id: file:///svn/mysql/tokudb-engine/src@5068 c7de825b-a66e-492c-adef-691d508d4ae1

storage/tokudb/ha_tokudb.cc

@@ -2437,7 +2437,12 @@ int ha_tokudb::read_row(int error, uchar * buf, uint keynr, DBT * row, DBT * fou
         unpack_row(buf, &current_row, &key);
     }
     else {
-        unpack_row(buf, row, found_key);
+        if (key_read && !hidden_primary_key) {
+            unpack_key(buf, found_key, keynr);
+        }
+        else {
+            unpack_row(buf, row, found_key);
+        }
     }
     if (found_key) { DBUG_DUMP("read row key", (uchar *) found_key->data, found_key->size); }
     TOKUDB_DBUG_RETURN(0);