Case when enabling abbreviation results in no useful mismatch info

[philomates]

The abbreviation feature (added in #214) seems to show no useful output for the following example

(require '[matcher-combinators.test :refer [match?]])
(require '[clojure.test :refer [is]])

;; normal behavior
(matcher-combinators.config/disable-abbreviation!)
(is (match? [#{2}] [#{1 2}]))
;; =>
;; expected: (match? [#{2}] [#{1 2}])
;;   actual: [#{(unexpected 1) 2}]

;; current abbreviation behavior
(matcher-combinators.config/enable-abbreviation!)
(is (match? [#{2}] [#{1 2}]))
;; =>
;; expected: (match? [#{2}] [#{1 2}])
;;   actual: [...]

I would expect the abbreviation feature, when enabled, to give something more like for the (is (match? [#{2}] [#{1 2}])) mismatch:

;; expected: (match? [#{2}] [#{1 2}])
;;   actual: [#{(unexpected 1) ...}]