Adding comment containing issue key results in badly formed URL

If I add a comment to a build that contains a URL to an issue it gets rendered incorrectly.

I added a comment like this:

http://jira.atlassian.com/browse/CONF-12801

which resulted in the comment here:
https://bamboo.extranet.atlassian.com/build/viewComments.action?buildKey=CONFFUNC-MAINSRCDISTRO15&buildNumber=111