It appears that min-key and max-key behave incorrectly (following Java that follows IEEE floating point convention):
Not sure how this should then propagate forward, but definitely not silently. Options:
1. [:b NaN] (the first item to generate the NaN)
2. NaN (this is changing the expected type)
3. ArithmeticException Operation with at least one NaN operand.
If this was to be patched the same as it was for min/max (http://dev.clojure.org/jira/browse/CLJ-868) it will probably result in option 1.
Likely All. Including older version of Clojure.