The changes in #12403 and #12513 subtly changed the behavior of Template
Haskell reification and splicing. While the old behavior was certainly buggy,
it's possible that there's code in the wild that depended on the old behavior
to work. To err on the side of caution, I'll postpone these changes to GHC
8.2.1 instead of having them merged into GHC 8.0.2.