Sereal/Json not faster than storable

[eserte]

On some of my smoker systems t/19.t fails:

#   Failed test 'Sereal faster than storable'
#   at t/19.t line 36.
# Looks like you failed 1 test of 7.
t/19.t .. 
Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/7 subtests 

or

#   Failed test 'Json faster than storable'
#   at t/19.t line 37.
# Looks like you failed 1 test of 7.
t/19.t .. 
Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/7 subtests