(PUP-2563) Exit with 1 on pre-1.9.3 ruby

Exit with 1 when running on versions of ruby before 1.9.3.
Merge pull request #3383 from joshcooper/ticket/master/PUP-2563-non-zero-exit

(PUP-2563) Exit with 1 on pre-1.9.3 ruby.