add test for values > typemax(UInt32)

[Ken-B]

from julia-users:
https://groups.google.com/forum/#!topic/julia-users/Jpj_Zb7EmcQ

Fixed in 28c1860. Should we add a test?

I haven't looked into the issue itself, but could have a look at the end of the week.

[stevengj]

The only issue is that a test for this takes a couple of minutes to run.