Add back at::_copy_from for use by XLA (#20783)
Summary:
XLA needs a way to override CPUTensor.copy_(XLATensor), but we only
dispatch on the "self" argument. This inverts the dispatch order when
"src" is an unhandled type.
Note that things like XLATensor.copy_(CPUTensor) never enter this
implementation.
cc dlibenzi
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20783
Differential Revision: D15443187
Pulled By: colesbury
fbshipit-source-id: 4ee93ba598ef0fed2a99c0683aae30cb50a1f99c
