Is this based on a short film?

Apparently it's just coincidence - the guy that made the short film was talking about it with Empire:

"Our Stitches preceded the feature film of the same name by several months. Ben and I are fans of Stephen King's IT and wanted to make a short involving some kind of twisted clown character, so we made the film our second short in the series, loosely basing it on the 'clown in the corner' urban legend. We then got a call from a producer, saying he thought there was potentially a feature to be had out of that character, so we set up a meeting and started fleshing out ideas. And the next day, there was an official announcement of another new clown movie… of course called Stitches. To say we were surprised is an understatement, but we don't believe it's connected: just pure coincidence... we hope! It's a shame though, because we do think our character is actually a better design than the Ross Noble clown. And we'd have played it very straight too, and very scary! It was good early lesson though, that you can't really get attached to anything you do, because someone else might just beat you to the post with it."

Are you thinking of "Clown (2013)?" It is being made into a feature set to release this year and is being produced by Eli (shudders) Roth.