Since JGit cannot use the "local" protocol (only git, ssh and https) we can't
use file:/... repositories in the same way as the other protocols. Formerly
we would copy the whole directory and use the copy as a local cache. But then
users are confused when they commit changes to the "remote" and they don't
show up in the server. It seems less confusing to simply use the local
repository as the basedir (although it does mean that ssh: should be used
if you are scaling up the config server).
Fixes gh-63
fecc7c8539