What do you mean by "versioning support for git dependencies"? We do support pulling in git dependencies based on a branch (I think tags work?)

We also support checking the version of the git dep.

It's fetching the dep that's the problem. Git has no uniform protocol for talking about versions, especially when it comes to resolving SemVer ("you asked for 0.2.1 but I also have 0.2.5, here you go")

If you want go-style import resolution use a local git dep. That works fine. It's specifically when you want all the features of cargo's version resolution -- which git doesn't understand -- you need to use a custom registry.