Prevent videos from occasionally being downloaded repeatedly forever

[xordspar0]

Once in a while, I’ll send the bot a video and it will download it again and again until I stop it or the server runs out of space.

[xordspar0]

Example

Video title: Fantastic DIY Speakers for less than $30!
Video link: https://m.youtube.com/watch?v=zdkyGDqU7xA
Time in logs: 2018-03-21T15:00:34-05:00
Notes: Someone sent me this video, and I forwarded it to Squirrelbot from that conversation.

[xordspar0]

Counter Example

Video title: Bulletin Board Stereo Speakers | Styrofoam Bluetooth
Video link: https://www.youtube.com/watch?v=zMCyF400l1c
Time in logs: 2018-03-26T14:53:15-05:00
Notes: I forwarded this link to Squirrelbot, but it did not get stuck in a loop.

[xordspar0]

Maybe Telegram is sending us multiple messages. Maybe we need to check the message ID to make sure we haven't received this message before.

[xordspar0]

If that's true, 6d97f35 will help us get to the bottom of it.

[xordspar0]

I learned from a conversation with Telegram bot support that if I don't respond with an HTTP status code of 200 in time, Telegram will try again. I have only been sending 200 OK after everything finishes. For long videos, the download takes longer than the timeout before Telegram tries again.