Print progress data for a slow git operation

[antoyo]

Hello.
When I have this git dependency https://github.com/dtolnay/syn, cargo update hangs when trying to fetch it.
I waited 30 minutes without any progress.
I'm able to clone it manually with git.
Here's the log from cargo update:

TRACE:cargo::sources::git::source: updating git source `GitRemote { url: "https://github.com/dtolnay/syn" }`
INFO:cargo::sources::git::utils: update submodules for: "~/.cargo/git/checkouts/syn-6f4912dca572d3ab/0aa50e0/"

I don't know if it is related to the other issues mentionning a freeze.
Thanks to fix this issue.

[alexcrichton]

I think this is just a case of libgit2 doing a slow clone. The syn repo has a submodule to rust-lang/rust, which takes a long time to clone.

[antoyo]

It seems this is it.
Should we provide some output so that the users know that something is happening when it's very slow?

[alexcrichton]

Certainly yeah!

[antoyo]

I think we can close this issue as cargo now shows a progress bar.