conda create with yml file doesn't work

```
> conda env create -f esgf-pub_env.yml
Collecting package metadata: done
Solving environment: failed

ResolvePackageNotFound: 
  - cdms2=3.1.0 -> esmf[version='>=7.1.*']
  - cdms2=3.1.0 -> esmpy[version='>=7.1.*']
```
Same error if I add `esgf` and `cdat` channels in the the yml header.