Previously the path preview misbehaved when typing dots on the first
shell word (e.g. executing a script in a parent directory). This
happened as the `(z)` parameter expansion flag does not expand to an
array rather a scalar. Because of that, `[-1]` returns the last
character.
Work around this issue by prepending LBUFFER with a dummy word, so that
it always contains at least 2 words.
Julian Prein
14f615f5e1
