Remove six dependency

[urishalit]

I removed the file gunicorn/six.py and added six as a requirement for the project.

The motivation for this was this issue.

I ran the tests locally and that ones that pass before change pass after it and vice versa, so I am sure the ones that are failing are due to a problematic test configuration (Or you have failing tests merged) - I tested this on our environment and it seems to work.

[berkerpeksag]

I don't think this is the correct solution. We should fix our vendored six if it's broken. It's too late to remove it from 19.x.

Also, your report doesn't give us any information about what exactly is broken in gunicorn/six.py. Is it the _winreg import issue or is it something else?

[urishalit]

Yes, the problem is _winreg.
Why isn't this the correct solution?

Why is it too late?

[tilgovi]

Why is it too late?

We would like to consider 19 in maintenance mode now, with a focus on releasing 20. Changes should be kept to a minimum to fix bugs. Updating our vendor copy of six is fine, but adding a dependency is more risky.

Gunicorn has six as a vendored dependency so that Gunicorn does not restrict what version of six applications can use and is not affected by any version of six used by an application running under Gunicorn. I believe we should keep it that way.

I think we could accept a PR to update the vendored version of six, assuming there are no changes that would case any fear of breaking something in Gunicorn.

[berkerpeksag]

What @tilgovi has said. I'd be happy to review and merge a PR that moves the _winreg import to the correct place.