Comment 1 for bug 1087804

If no slaves are found, and recursion-method is not "none", and --quiet < 2, then this warning is printed and exit status is non-zero:

"Diffs cannot be detected because no slaves were found. Please read the --recursion-method documentation for information."

I thought about making the tool die at this point so it doesn't do a bunch of useless work, but it could happen that slaves do exist but aren't found, so checksums do replicate, then the user can --replicate-check-only later to see if there are diffs.

I think non-zero exit status is correct because some users may be checking it rather than the output, in which case this will indicate that despite zero diffs, there was a problem that explains why there are zero diffs.