Log an INFO-level message when SIGINT received

[Makman2]

Hi ;)

I'm recently experimenting with your nice bot. However, I stumbled upon this during my "learning-process":

I've created a bot, it worked normally. I just did updater.start_polling like in the examples, but without using updater.idle() (I thought first start_polling is blocking). Exiting with CTRL+C worked immediately, but has thrown a KeyboardInterrupt.
After a while I found the idle() function, but I was actually a bit confused of CTRL+C's behaviour, because I've configured logging with a minimum level of INFO. So I've seen nothing when I pressed the keys. The bot actually needs a while to shutdown, and because nothing was logged I assumed the SIGINT signal wasn't received (/ assuming due to internal threading stuff not properly processed), so I pressed always CTRL+C two times causing a SIGTERM which worked immediately.
SIGINT notifications are only visible when enabling DEBUG-level logging. I would suggest to add an INFO message, that tells something like Received SIGINT, shutting down..., so nobody is worried ;)

[JosXa]

@Makman2 To make it clear, this is all intended behavior. I kind of see your point, but it's probably not something that the library should spam into log files for users that collect them for later (if I'm making any sense). The issue is debatable, but since it's an event that clearly belongs to the "debugging" stage of application development, it makes sense to have it displayed only when debug logging is enabled, which every user should do at least once in his contact with ptb, since this offers many other clues to the internals of ptb that would fall into the same category of what the library does under the hood.

[Makman2]

it's an event that clearly belongs to the "debugging" stage of application development

This is the thing where I'm not so sure ;) It's kind of right that you usually keep your bot alive forever once it's in production state, however even then you sometimes have to shut it down (and I'm not sure if a production state bot should run in DEBUG mode). An indication might just help seeing that everything went fine.
Also a SIGTERM signal gets displayed as a WARNING, so not sure if it's better to display SIGINT for sake of consistency (but not as a warning).

The issue is debatable

Indeed :) Personally I would like to receive an info, that's why I try to find arguments for it :)

[Eldinnie]

Hi,

I tend to lean towards making this a INFO-level message. It's not really a spammy message (only occurs on the SIGINT signal) and alerts the user that the signal is received and the bot is closing down.
@jh0ker @tsnoam @bomjacob thoughts?

[jh0ker]

@Eldinnie I Agree

[tsnoam]

@jh0ker I agree too

[JosXa]

You got my blessing. @Makman2 would you be willing to make a PR? :)

[Makman2]

I'll try, currently Christmas and stuff, and Google Code-In still running on my main open source project :) But shouldn't be too hard I guess ;)