Add flexiblility for more specialized targets

Actually ShellCheck was *right* that the variable expansion needed to
take care of spaces in paths, but the fix (g:b68913c in ffoo repo) was
totally wrong and only broke things.

Lessons learned:

 *  *Do* run ShellCheck et al., but still **DO CAREFULLY** consider
    effects in the particular context.

 *  Too much coffee, repetitive work *and* distraction is a good way
    to ask for trouble.