-c pytorch means from the Pytorch anaconda channel, i.e. packages prepared by the PyTorch team (sometimes I think Soumith himself does that).
The pytorch and torchvision selects the latest packages available on that channel (where the stable releases are put, so currently 1.3 / 0.4, as you say).
The cuda library is provided in a separate package cudatoolkit of which you explicitly select version 9.2 on the command line.)
The end result is as you describe it
Best regards
Thomas