Add comment to warn about fetchThreadPermissionsBlob
Add comment to warn about fetchThreadPermissionsBlob

Test Plan: Nothing to test, just comment added

Reviewers: ashoat, palys-swm

Reviewed By: ashoat

Subscribers: zrebcu411, Adrian

Differential Revision: https://phabricator.ashoat.com/D388

Ashoat/squadcal,Ashoat/squadcal,Ashoat/squadcal,Ashoat/squadcal,Ashoat/squadcal,Ashoat/squadcal,Ashoat/squadcal