UPDATE
This issue was fixed by Discourse team and is no longer an issue. no need to read, enjoy hanging with friends or family.
I'm working with some soundcloud files that I want to oEmbed in a discourse message board. The urls are https but when you hit the soundcloud enpoint with a https, it causes a 500. For example, the url https://soundcloud.com/smitty1138/the-ink-spots-maybe
See more info here: http://meta.discourse.org/t/curious-about-onebox-and-soundcloud-support/5365
edit 1
so you can see an example here: http://foodiespot.com/t/category-definition-for-favorite-restaurants/4
and:
Discourse is using onebox which is sending out https requests as you can see in chrome. There might be an issue with how they sound out https requests.
It very well could be an issue with how urls are encoded.
This issue was fixed by Discourse team and is no longer an issue