Parcel: warnings for 'REPLY' statuses

Comment a warning for this hack to add data into statuses. I've also
heard from jsharkey@ in the past a need for a generic solution here.
At a minimum, this prevents new bugs/bad interactions with native
code.

Bug: 235006086
Test: N/A
Change-Id: I3bcb2b8638803cde0f6ef257b65bb9456843abf7