[spec] spec.test/check returns the wrong value of :failure for failing tests

When trying to manually wire clojure.test and spec for fdef'ed functions, I realized that spec.test/check returns a map with [:failure false] for failing tests. I'm (almost) sure it should return true, because spec.test/abbrev-result receives as argument the return of spec.test/check and tests the value of :failure. I couldn't produce a case where spec.test/check returned [:failure true] for failing tests. For information it returns a map without the key :failure for passing test.

Here's a simple reproduction case in the REPL :

(defn foo-fn [x] "bar")

(s/fdef foo-fn
:args (s/cat :x any?)
:ret string?)

(stest/check `foo-fn) ;; => no error, normal small map printed, no :failure entry

(defn foo-fn [x] 1)

(stest/check `foo-fn) ;; => full error map, with :failure equals false. :failure shown below

(-> (stest/check `foo-fn) first :failure) ;; => false