Patch from Joe Loser. Several unit tests meaning to test the behavior of lvalue insertion incorrectly pass rvalues. Fixes bug PR # 27394 Reviewed as https://reviews.llvm.org/D44411 git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@329541 91177308-0d34-0410-b5e6-96231b3b80d8