autotests/exec/18-io-not-allowed/01.plof: Fixed this test case so that it won't fail when it oughtn't (it catches the correctly-thrown exception)
autotests/exec/18-io-not-allowed/01.plof: Fixed this test case so that it won't fail when it oughtn't (it catches the correctly-thrown exception)

GregorR/plof3,GregorR/plof3,GregorR/plof3,GregorR/plof3