I got both ahead of and behind the times.
In the updated Nemeth Code, which is currently neither approved nor published, it will say that since the colon meaning "such that" is still a colon–a mark of punctuation–we should treat it as such and use a punctuation indicator before it (unspaced from the material it follows), and space after it.
The only currently approved and published rule reference we have is example (9) in §27.f [on print page 34] of the 1972 Nemeth Code, which shows a colon that means "such that," and the colon is totally unspaced. I always try to recommend following the currently approved and published rule.
It will be soooo exciting when the updated Nemeth Code is published!