Merge branch 'run-program-errors' into 'master'
Complete branches in %NORMALIZE-IO-SPECIFIER. Per comments in !46 I think there is a danger that `%NORMALIZE-IO-SPECIFIER` could inappropriately return `NIL` when there is an unexpected set of `*FEATURES*`. I'll try to have a look and see if there are other cases like this. Elias, will you have a peek at what I've done here? See merge request !49