This is strictly an upstream issue, but posting it here since people might run into it and come looking for a solution.
https://clojure.atlassian.net/browse/CLJS-3097
Long story short: tools.reader changed the two-arity version of read+string to be in line with read+string in clojure.core
;; before
(read+string reader opts)
;; now
(read+string opts reader)
And this is used by the clojurescript prepl, which we rely on. So for the time being you have to stick to tools.reader 1.3.0.