Clear out request-local globals at the beginning of each request
The rpc server keeps the ExecutionContext alive across requests to
reduce startup costs. Unfortunately, we weren't clearing $_SESSION, $_GET,
etc... at the beginning of the request. This was making us think that most of
the http headers in most requests were duplicates, and emit a warning where the
option is enabled. It's also generally bad practice to leak this stuff between
different requests.
Reviewed By: @markw65
Differential Revision:
D1010456