Function control_path_option 

fn control_path_option(dir: &Path, dest: &SshDest) -> String

ControlPath= for dest’s shared connection in dir: <name hash>-%C. ssh’s %C hashes the user, host and port ssh resolves, not the name it was given, so two aliases for one account (one with a key, one password-only) shared whichever connection logged in first, and the password-only one got in without asking (#4513). The connection’s own name keeps them apart; %C stays so an alias pointed elsewhere gets a new connection.