Conda solver not handling developmental (and maybe pre-releases) as expected.

[afranchuk]

According to https://www.python.org/dev/peps/pep-0440/#handling-of-pre-releases, I would have expected a constraint of ~=0.1 to match an available 0.1.0.dev0 when there is no 0.1.0 version available. I do realize they have a SHOULD clause rather than MUST, but I'd expect the libsolv implementation to try to aspire to that. I am using mamba (micromamba actually) but I believe they just pass everything to libsolv (@wolfv could probably comment more).

I haven't tried with prereleases (alpha/beta/rc) to see whether that works as expected, though I'd expect it does and the .dev case is just being overlooked, since you have to read a little closely to realize that the PEP440 wording does include .dev as a prerelease specifier of sorts.