Improve tracing slightly
Improve tracing slightly

(cherry picked from commit cbe59d89f2f1cc41147fabb4a4c58126152bef7f)

hferreiro/replay,lukexi/ghc-7.8-arm64,hferreiro/replay,hferreiro/replay,hferreiro/replay,hferreiro/replay,lukexi/ghc-7.8-arm64,hferreiro/replay,lukexi/ghc-7.8-arm64,hferreiro/replay,lukexi/ghc-7.8-arm64,lukexi/ghc-7.8-arm64