Fix #47: hostname is set in utmpx by login
Fix #61: login handles utmpx on Mac OS X
Obsolete #190: motd is now handled by login
Fix #193: login correctly sets cwd to home
Obsolete #199: shell lookup is done by login
Fix #201: login understands username maps
Fix #216: .hushlogin is handled by login
As hostnames can no longer be set dynamically, the hostname is now statically set to the PID of mosh-server without a hostname (which happens to fix the truncated PIDs reported on FreeBSD by zi).
I seriously doubt that this commit will ever be merged to upstream, however, as it requires mosh-server to be setuid root (upstream seems against mosh-server even having temporary priviledges).