EDIT: workaround solution at #8172 (comment).
EDIT: more precise explanation of this bug at #8172 (comment).

While trying to install delta, I got this error:

cargo build --release

Updating crates.io index
error: failed to get ansi_colours as a dependency of package git-delta v0.1.1 (/home/marcospb19/delta)
Caused by:
failed to fetch https://github.com/rust-lang/crates.io-index

Caused by:
failed to authenticate when downloading repository
attempted ssh-agent authentication, but none of the usernames git succeeded

Caused by:
error authenticating: no auth sock variable; class=Ssh (23)
make: *** [Makefile:2: build] Error 101

I know almost nothing about Rust or Cargo, sorry if this issue isn't very clear.
Why would cargo use ssh to make this update?

Notes

Cargo and Rust --version:
1.43.0

OS:
Arch Linux