[t] Revised the "Garbage collection shouldn't sweep up singleton PMCs" test to use the Env PMC instead of the now-removed Random PMC.
[t] Revised the "Garbage collection shouldn't sweep up singleton PMCs" test to
use the Env PMC instead of the now-removed Random PMC.

git-svn-id: 6e74a02f85675cec270f5d931b0f6998666294a3@40572 d31e2699-5ff4-0310-a27c-f18f2fbe73fe

ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot,ashgti/parrot