pypi: Deployment fails on windows because of '-z was unexpected at this time.'

[metthal]

I've recently tried deployment using Travis and Windows. The error I get when installing deployment requirements:

$ ruby -S gem install dpl
Successfully installed dpl-pypi-1.10.7
Parsing documentation for dpl-pypi-1.10.7
Installing ri documentation for dpl-pypi-1.10.7
Done installing documentation for dpl-pypi after 0 seconds
1 gem installed
Installing deploy dependencies
failed to deploy
-z was unexpected at this time.
Couldn't install pip, setuptools, twine or wheel.

It seems like it tries to use cmd instead of bash. I've dig into the source code and found this so I think that -z comes from this line. I don't know if it is enough to just prefix this command with bash -c. What I am afraid of here is that Windows uses git bash for its build scripts and cmd is used here so I am not sure whether virtual environment would be even preserved here.

[stale]

Thanks for contributing to this issue. As it has been 90 days since the last activity, we are automatically closing the issue. This is often because the request was already solved in some way and it just wasn't updated or it's no longer applicable. If that's not the case, please do feel free to either reopen this issue or open a new one. We'll gladly take a look again! You can read more here: https://blog.travis-ci.com/2018-03-09-closing-old-issues

[metthal]

The issue hasn't been fixed yet.