Allow prereleases if the specifier contains a prerelease version

[sarugaku]

Allow prereleases if the specifier contains a prerelease version

[techalchemy]

For the purpose of pip or pep440 compliance you should never have to enable this. If you explicitly pin a prerelease version then you get that version whether you enable prereleases or not.

[uranusjr]

Yeah, that is working now, but I’m thinking about something else, e.g. if the user has something like django<2.1b3 it is likely the intention to include prereleases? Maybe? I don’t know, really, so this is more like an open question waiting for someone to think through…

[techalchemy]

I actually don’t think that’s the case, they’d probably still depend on stable versions. We can find out though

[techalchemy]

Also I believe pep 440 details the behavior around this and it explicitly states that you shouldn't infer this behavior from a strict pin