Remove overly strict assertion for type demotion of scalars. (#38001)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/38001
Reviewed By: ZolotukhinM
Differential Revision: D21445921
Pulled By: resistor
fbshipit-source-id: efe441eea5c2996d919c5c2621b13a379e68accb
