Merge branch 'jg/credential-cache-chdir-to-sockdir'

The "credential-cache" daemon process used to run in whatever directory it happened to start in, but this made umount(2)ing the filesystem that houses the repository harder; now the process chdir()s to the directory that house its own socket on startup. * jg/credential-cache-chdir-to-sockdir: credential-cache--daemon: change to the socket dir on startup credential-cache--daemon: disallow relative socket path credential-cache--daemon: refactor check_socket_directory