strip-extra-keys-transformer not working with s/or if ors predicates are non- map validating specs

[Tyler Nisonoff]

This is similar to Issue 178 (Fixed by PR 219, but for a specific case.

I'm not sure if this is intended, but it was surprising to me.

Consider the following case where we want to allow something like either {:a 1} or {:b "foo"}

  (s/def ::a int?)
  (s/def ::b string?)
  (s/def ::c (s/or
               :a (s/keys :req-un [::a])
               :b (s/keys :req-un [::b])))
  ((s/valid? ::c {:a 1})
  ; => true
  (st/coerce ::c {:a 1} st/strip-extra-keys-transformer)
  ; => {}

However, If i change ::c to:

(s/def ::c (s/or
               :a (st/spec (s/keys :req-un [::a]))
               :b (st/spec (s/keys :req-un [::b]))))

NOTE: the st/spec s

Now we get:

 (s/valid? ::c {:a 1})
  ; => true
  (st/coerce ::c {:a 1} st/strip-extra-keys-transformer)
  ; => {:a 1}

My expectation is either of these two should be able to be coerced, is that correct?