In form, a derivative of tetch n., but that word being both less common and apparently of later appearance, may be a back-formation from this. Derivation < tache n.1 (in Middle English tecche, 16th cent. tetche) has been suggested; but there are difficulties both of form and sense.
1. Easily irritated or made angry; quick to take offence; short-tempered; peevish, irritable; testy. (Cf. touchy adj., which has been associated with this from early in the 17th c.)
a. Of persons.
b. Of qualities, actions, etc.: Characterized by or proceeding from irritability.
2. fig. Of land: see quots. dial. (OED)
"And so, in due course, the alien craft arrive: tetchy pilotless drones in the shape of pizzas, from which individual slices peel off to launch spicy, deep-crust attacks on defenseless mortals."
- Anthony Lane, "Out There: 'Battle: Los Angeles' and 'Paul'", 21 March 2011 The New Yorker