Looking at the compileall module, it appears that -f and options other than -b have never (or, at least, for a long time, not) been supported when directories or files are not supplied and it defaults to <directories from sys.path>.  Note the call in main() to compile_path vs those to compile_file or compile_dir.  I'm not sure if there was a good reason for the difference but it seems like a bug now.  Would you care to work on a patch and/or tests?