Fix oscillation in coalesceInsertedDataDependencies (#20833)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20833
Att. The algorithm is still "horrendously inefficient". But since we are sunsetting Nomnigraph, I just did the minimal fix here.
Reviewed By: tracelogfb
Differential Revision: D15463880
fbshipit-source-id: 413a1280a92c1923ba49031177816a2d5f888575
