Fix parent process detection in batpipe

[ebugusey]

Less is called with a filename, and if we basename CMD of less we get a basename of a filename, not a less executable. I think it's just a type that basename was piped to cut, CMD should be cut'ed before processed by basename.

As parent_executable is only used by batpipe, we can just cut CMD and extract program name.

[nigelgbanks]

@ebugusey cheers for this!