PyCall does not use virtualenv

I'm running Python 3.7.3 and Julia 1.1.1 (2019-05-16). I have a virtual environment set up for python and PyCall is unable to import the packages installed there. In addition, when I run

```julia
py"""import site
print(site.getsitepackages())"""
```

I get the site packages folder of my main install and not the environment one. I can also import packages if they are installed on my system's Python.

When adding PyCall I have my environment activated. I have also tried setting the ENV["PYTHON"] and running `Pkg.build("PyCall")` as well with no change.

I am on Windows 10.