To reproduce:
- Start typing a message.
- Press Shift + Enter to create a new line in the same message.
- Type a link on this line (e.g.
[foo](http://example.com)
) - Send the message.
- You will notice that the message appears as
[foo](http://example.com)
instead of appearing asfoo
with the text linked.
Here's an example: http://chat.webapps.stackexchange.com/transcript/message/907#907