`comments-time-machine-links` doesn't work properly with multiple branches #2903

URL where the bug appears: the issue you're in right now (look below for the link with the clock that doesn't work)

Extension uses HEAD@{2020-03-19T21:24:30Z} as the revision, which prevents this from working properly when the closest commit to that date is from different branch.

Using branch_name@{DATETIME} should work here, i.e. https://github.com/Cog-Creators/Red-DiscordBot/blob/develop@{2020-03-19T21:24:30Z}/cogs/downloader.py links the user to proper address.

https://github.com/Cog-Creators/Red-DiscordBot/blob/develop/cogs/downloader.py