fix selecting GPUs using CUDA_VISIBLE_DEVICES (#2739)
fix selecting GPUs using CUDA_VISIBLE_DEVICES (#2739)

* fix https://github.com/PyTorchLightning/pytorch-lightning/issues/2407

* Update pytorch_lightning/trainer/distrib_data_parallel.py

Co-authored-by: Jirka Borovec <b903e28b3fb12ead55c25f3a7816376be3bd063c@users.noreply.github.com>

Co-authored-by: Jirka Borovec <b903e28b3fb12ead55c25f3a7816376be3bd063c@users.noreply.github.com>
williamFalcon/pytorch-lightning,williamFalcon/pytorch-lightning