console.lua: don't reinsert the next characters on complete

This avoids inserting the characters in front of the cursor again when
completing to text already in front of the cursor.

This is important after 2f271a92de made Enter automatically insert the
first completion.

player/lua/console.lua

@@ -1431,7 +1431,8 @@ cycle_through_suggestions = function (backwards)
 
     local before_cur = line:sub(1, completion_pos - 1) ..
                        suggestion_buffer[selected_suggestion_index] .. completion_append
-    line = before_cur .. strip_common_characters(line:sub(cursor), completion_append)
+    line = before_cur .. strip_common_characters(line:sub(cursor),
+        suggestion_buffer[selected_suggestion_index] .. completion_append)
     cursor = before_cur:len() + 1
     update()
 end