Pkg: private repository usage and keys

Thanks for this @GunnarFarneback. As you point out, apparently using the PEM SSH key format works, but not the default OPENSSH format (which I was using) because (quoting you)

LibGit2 gets its ssh functionality from libssh2 , which indeed is less capable of taking the ~/.ssh configurations into account than the ssh command line interface used by the git command line interface.

But it seems like @StefanKarpinski is working on improving this.

Apparently the above solution involving ssh-agent somehow makes incompatible keys available to libssh2 via an intermediary.

Just thought that summarizing the situation might be helpful for the next confused googler.