#inst is defined by edn to employ the RFC-3339 format (https://github.com/edn-format/edn#inst-rfc-3339-format)
This can fail for years prior to 1000:
Compare with Clojure:
CLJS-3263-3.patch rebaselines.
Depends on for the unit tests in this ticket to pass.
Note that the trickery that Eric indicates above is addressed in CLJS-3291.