[phobos] Unittest failure in std.algorithm, seemingly CTFE-related

[Jonathan M Davis]

> After I merged a number of pull requests, the phobos unittests don't
> compile anymore. There's no indication of a source file and line causing
> the trouble.
> 
> Don, could you please give it a look? Thanks!

The recent changes in std.datetime cause it to show up for some reason (I have 
no idea why, given that the error appears to be in std.algorithm when 
compiling its unit tests), but it didn't happen with dmd 2.052. So, it's 
clearly caused by recent changes to the compiler.

- Jonathan M Davis