Prefix adjustment

caveats per IRC: 
 * inserts a spurious space when the string is empty
 * presupposes all users want to use space as their separator (which [Aphyr] likes to encourage but tries not to mandate)

Former is addressed with commits now present.  Not real happy with my failure to shadow "report" correctly, but tests pass as opposed to the prior state.  Happy to make further alterations based on feedback.