Could you update your conda and rerun the installation?
This is what I get in a new environment:
## Package Plan ##

  environment location: /home/pbialecki/anaconda3/envs/tmp

  added / updated specs:
    - cudatoolkit=9.2
    - pytorch==1.2.0
    - torchvision==0.4.0


The following packages will be downloaded:

    package                    |            build
    ---------------------------|-----------------
    cudatoolkit-9.2            |                0       233.9 MB
    pytorch-1.2.0              |py3.7_cuda9.2.148_cudnn7.6.2_0       371.3 MB  pytorch
    torchvision-0.4.0          |        py37_cu92         9.8 MB  pytorch
    ------------------------------------------------------------
                                           Total:       614.9 MB

The following NEW packages will be INSTALLED:

  cudatoolkit        pkgs/main/linux-64::cudatoolkit-9.2-0
  ninja              pkgs/main/linux-64::ninja-1.9.0-py37hfd86e86_0
  pytorch            pytorch/linux-64::pytorch-1.2.0-py3.7_cuda9.2.148_cudnn7.6.2_0
  torchvision        pytorch/linux-64::torchvision-0.4.0-py37_cu92

I thought the single = for cudatoolkit=9.2 would create the issue, but apparently it’s also working like this.