Do you really need GitHub that much? How about a solution to host and share your version-controlled code with tools almost completely from OpenBSD base?

Feature Self-Hosted CVS GitHub
Review head in browser? Yes (cvsweb) Yes
Public option to check out source code? anoncvs git clone
Submit diffs? Pull Requests
Platform License Open-Source Proprietary/closed-source
Private Repositories Easy (leave out anoncvs) & free Paid
Hosted by You Microsoft
Export to the other SCM system? Yes (cvs2gitdump) None known (git->cvs)
Need to create account to contribute? No (check out with anoncvs, submit diff by email) Yes
Written in C & shell script; Perl (cvsweb) git: C, Shell, Perl, Tcl, Python. GitHub: Ruby, Erlang
Webpage uses cookies No (cvsweb) Yes
Emojis? No Yes
Creates and maintains bloated software? Up to you Yes: Electron, Atom
Graphical statistics on repos e.g. cvsplot In browser interface
Issue tracking e.g. GNATS In browser interface

See also here for more arguments for cvs.

Status of opencvs