Let pysetup list exit with a non-zero code when no result is found (#11409).

“pysetup list” or “pysetup list --all” will continue to return 0 if no
distribution is found (it’s not an error), but “pysetup list
some.project” will now exit with 1 if no matching installed distribution
is found.  Based on a patch by Kelsey Hightower.
1 file changed