Yes, that's indeed how it is.
github.com
github.com
But on this one, is it documented? There are lots of valid reasons to make a tradeoff like this. If you've made it, and put up big warnings about it, then failure to respond to those bug reports is quite reasonable.
http://deron.meranda.us/python/comparing_json_modules/number...
It's probably not a trivial fix/addition and might end up costing the library some of it's speed.