cmd/go: go get hangs when credential.helper cache is set

[OneOfOne]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

Go 1.8.3

What operating system and processor architecture are you using (go env)?

CentOS 7 / Debian 8 linux/amd64

What did you do?

$ git config --global credential.helper cache
$ go get -u github.com/private/private-repo
github.com/private/private-repo (download)
Username for 'https://github.com': OneOfOne
Password for 'https://OneOfOne@github.com': 
^C

Trying to go get a private repo while git credential.helper is set to cache hangs after asking for the username/password.

What did you expect to see?

go get to finish downloading the repo and all its deps.

What did you see instead?

The void, it spoke to me in ways that can't be fully explained.

[ianlancetaylor]

Can you show us the output of go get -x -u github.com/private/private-repo ? That will at least show us the exact git command that is hanging.

[OneOfOne]

$ go get -x -u ./...
cd /home/private/src/github.com/private/private-repo
git config remote.origin.url
cd /home/private/src/github.com/private/private-repo
git pull --ff-only
Username for 'https://github.com': OneOfOne
Password for 'https://OneOfOne@github.com':

Here's the thing though, git isn't even stuck, it exits after entering the password (after successfully pulling any updates to that repo) then nothing, go get just hangs there.

I verified that by ssh'ing in and running ps aux | grep git.

[OneOfOne]

Ok something weird just happened, I had forgotten go get running since earlier, it resumed and checked few repos then got stuck again when I had to enter the user/pass again.

Not sure how long it was stuck for but at least 10 minutes, it might be something to do with having to do with entering the user/pass.

[OneOfOne]

Random thought, is this somehow related to #20865?

[bcmills]

@OneOfOne, next time you get the hang, could you kill cmd/go with SIGQUIT and attach the goroutine dump that it (hopefully) produces?