Bad stitch name autocomplete with full local reference

If I make a local reference to an as-yet-unwritten stitch using a full address rather than a local relative address (which is valid Ink), when I come to write the stitch it tries to autocomplete the stitch name with the full address (which is not valid Ink).

Reproduced by typing the following (and tab-completing after the final character):

```
-> top_knot
=== top_knot

some text
-> top_knot.first_stitch

=f
```