[WIP] Added methods to edit a Github bug

Review Request #9621 — Created Feb. 11, 2018 and discarded — Latest diff uploaded


Review Board


Modified review_request_closed method to close the bug when the Review
Request is closed if enable_closing_remote_bug is set to True.

Added methods to github.py and hostingservices.py to enable sending an
HTTP Patch request in order to allow closing a Github Issue.