Fix out-of-topological-order issue in Nomnigraph (#19458)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/19458
The algorithm in https://fburl.com/ggh9iyvc fails to really ensure topological ordering of nodes. The fix is ugly but effective. I think we need a real topological sort to fix this issue more nicely. Mikhail Zolotukhin, Bram Wasti.
Differential Revision: D15011893
fbshipit-source-id: 130c3aa442f5d578adfb14fbe5f16aa722434942
