Install virtualenv if and only if it's not available

[philip-bl]

Hi. I've just installed GIMP-ML-Hub. Its user interface is indeed better than that of the original version, nice work :)

I use Debian 10 (Buster). I have virtualenv installed via apt - it's provided by python3-virtualenv package. Thus, I saw the line python3 -m pip install --user -U virtualenv || python3 -m pip install -U virtualenv # fuck this, I have virtualenv from apt in install.sh and removed it, and everything worked. I wanted to avoid that line, because conflicts arise if you have a python package installed both from apt and from pypi. So, can you modify this line so that it installs virtualenv via pip if and only if the there is no virtualenv package installed yet?

[valgur]

Hi! Sorry, I did not notice your message until now. I agree, the script should first check whether virtualenv already exists and then prefer the apt version if it does not. Thanks for mentioning this.