make a sandbox test much less likely to fail
make a sandbox test much less likely to fail

Give it 20 seconds to run out of memory insteda of 2 seconds. The
test is still non-deterministic, though.

mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket