[IMCC] Avoided a memory corruption error when switching namespaces to the *current* namespace in PIR: IMCC assumed that freeing the old SymReg was always valid.  This isn't the case if it's the *same* namespace and the *same* SymReg. See TT #992, filed by Jonathan Leto.
[IMCC] Avoided a memory corruption error when switching namespaces to the
*current* namespace in PIR: IMCC assumed that freeing the old SymReg was always
valid.  This isn't the case if it's the *same* namespace and the *same* SymReg.
See TT #992, filed by Jonathan Leto.

git-svn-id: 6e74a02f85675cec270f5d931b0f6998666294a3@41242 d31e2699-5ff4-0310-a27c-f18f2fbe73fe

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