http://tholman.com/github-corners/ is another, which gives you straight SVG to inline. This one with a couple of minutes of minification and inlining comes to about 1 170 bytes (no gzip); that one after similar time comes to about 985 bytes and more accessible (see its aria-label/aria-hidden) if you remove the fancy animation which is a bonus.

(I confess I’m addicted to shaving bytes.)