explicitly provide memory format when calling to clone() at prune.py (#29593)
Summary:
Currently clone() has parameter memory_format with default value as Contiguous.
In the future it will be changed to different default memory format - Preserve.
To avoid any potencial issues, specify memory_format explicitly
Pull Request resolved: https://github.com/pytorch/pytorch/pull/29593
Differential Revision: D18439783
Pulled By: ifedan
fbshipit-source-id: e7ed6c19ee227990214d44c562c26a7250981324
