... because:
t/20-zombie.t ............ 3/32 # $SIG{CHLD} = 'IGNORE'
# $cmd->is_terminated should warn
t/20-zombie.t ............ 13/32 # $cmd->close should warn
t/20-zombie.t ............ 24/32 # hunting for zombies
# Failed test 'process 30479 is still alive'
# at t/20-zombie.t line 149.
# Looks like you failed 1 test of 32.
t/20-zombie.t ............ Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/32 subtests
You might want to look at it.