list python package dependencies without loading them?

Say that python package A requires B, C and D; is there a way to list A → B C D without loading them ?
Requires in the metadata (yolk -M A) are often incomplete, grr.
One can download A.tar / A.egg, then look through A/setup.py, but some of those are pretty gory.

(I'd have thought that getting at least first-level dependencies could be mechanized; even a 98 % solution would be better than avalanching downloads.)