Fix bug in docker builder
Fix bug in docker builder

It seems that curl in nixos lowercases all headers, but curl in
archlinux does not.

KaminoDice/vagga,joehillen/vagga,popravich/vagga,popravich/vagga,KaminoDice/vagga,tailhook/vagga,joehillen/vagga,tailhook/vagga,rrader/vagga,tailhook/vagga,joehillen/vagga,KaminoDice/vagga,rrader/vagga,tailhook/vagga,joehillen/vagga,popravich/vagga,rrader/vagga,popravich/vagga