Fixes missing commas where it wasn't immediately apparent whether
"requests" was being used as a verb or a noun.

Change-Id: Ic8c99b4f46475f40a6160d26a3cd11c215940dd5
GitHub-Last-Rev: 1becf6fabeb6f928e37526e96297dd60397ccf9b
GitHub-Pull-Request: golang/go#27649
Reviewed-on: https://go-review.googlesource.com/135135Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>