When trying to clone ANY repository via https from github, we get:
git clone https://github.com/rails/rails.git
Cloning into rails...
remote HEAD refers to nonex
the packages noted above can be found here:
I used these versions and was able to use git behind a proxy without issue:
$ sudo dpkg -i libp11-kit0_0.10-1_amd64.deb libgnutls26_2.12.14-5ubuntu2_amd64.deb libcurl3-gnutls_7.22.0-3ubuntu2_amd64.deb