On Feb 23, 2017, at 5:31 PM, C Anthony Risinger <anthony@xtfx.me> wrote:

Yeah I'm pretty sure the bigger problem was version-less reqs eagerly selecting a version (eg. latest) incompatible with later requirements provided by a different package, but then treating them as hard reqs by that point. I'll defer to you on how pip deals with things today.

I'll try to resurface a concrete example. I know for certain pip at that time (circa 2015) was capable of installing a set of packages where the dependency information was not solvent, because I pointed it out to my team (I actually think python-dateutil was involved for that one, mentioned in another post).