Cannot pass lambdas to clojure-indent-function

[arichiardi]

Expected behavior

The following should work in define-clojure-indent

(trace-handlers (lambda (&rest _) 0))

Actual behavior

It fails to trigger the right case branch.

Steps to reproduce the problem

(define-clojure-indent
  (trace-handlers (lambda (&rest _) 0)))

clojure-mode version information

clojure-mode (version 5.3.0)

The problem seems here where functionp returns nil as lambda is a special form.