Function refresh 

pub fn refresh(exe: &Path) -> Outcome

Re-point this install’s other name at the binary an update just replaced.

Best-effort by design: the second name is a convenience, and an install that never had one must not grow one behind the user’s back - KASL_NO_ALIAS is their choice to keep. So this only acts when the counterpart is already there, and reports what it did for the caller to print.