Updating tools.namespace dependency to 0.2.1 or later allows Clojure 1.9.0-beta2 to work
By "work" I mean that the command "lein with-profile +1.9 test" doesn't throw exceptions, and the tests pass.
cheshire depends upon test.generative 0.1.4, which uses an old version of tools.namespace that has some ns forms that fail the Clojure 1.9.0-beta2 spec checking for ns forms.
Through trial and error I found that forcing a dependency on version 0.2.1 of tools.namespace in cheshire's project.clj file doesn't break test.generative's use of it, and doesn't cause any of Clojure 1.9.0-beta2's ns form spec checking to fail.
Hmm.. okay, I can push the tools.namespace change in the short term.
Long term, it would be good to upgrade test.generative. It's disappointing that a minor release (going from 0.1.4 to 0.5.2) contains a breaking change that prevents it from working (with a not-helpful error message also)