[plt-scheme] Can compile-omit-paths return an error message if a path is given that isn't "immediate"?

The compile-omit-paths variable in info.ss files is a little subtle: I
didn't realize before that it only filters out immediate
subdirectories, and not any nested subdirectories.  If I have
directory structure like:

    project/
    project/info.ss
    project/helper-module
    project/helper-module/test

then to keep setup-plt from touching anything in
project/helper-module/test, it appears ineffective to try putting

    (define compile-omit-paths '("helper-module/test"))

in project/info.ss.

Rather, I've had to create a separate project/helper-module/info.ss
file with the content

    (define compile-omit-paths '("test"))


Is this a correct understanding of the meaning of compile-omit-paths?
If so, can we include this example in the documentation?  This came up
a lot for my own projects, and I couldn't figure out what was going
wrong until recently.


Also, it seems like info's checking of compile-omit-paths should point
out an error if there's a nested sub path in compile-omit-paths, since
that usage is erroneous.