dub dependency version problems

[Laeeth]

Unfortunately I don't understand things well enough to reduce to a simple test case. You can speak to John Colvin who may understand what's going on a bit better. But I have had some nightmarish cyclical dependency problems with dub where the packages of a project reference different versions of another package (eg vibe-d). One problem is that the error reporting from dub is very unhelpful:

Root package server references unknown package vibe-d

This seems to be the consequence of subpackages referencing different versions of vibe-d.

Another problem is that dub (build and verbose) gets stuck in a loop and never finishes.

I build a primitive tool here to report all versions used by dub.sdl or dub.json projects in subdirectories of a particular directory, and this helps a lot. Will post gist shortly.

[Laeeth]

Gist is here: https://gist.github.com/Laeeth/9e62861414329721ca39 sort doesn't work, but I didn't bother figuring out why.

[MartinNowak]

Might be related to #652.

[Geod24]

This looks a lot like #1706 / #1217 . Regarding the need for more information on dependencies, Jan is working on #2359