There is a work-around solution you can use to accomplish this. Check out this quick screencast for details.
http://autode.sk/1DZSz1T
You may consider voting up the below Idea in the IdeaStation if you're interested in seeing this functionality implemented.
http://forums.autodesk.com/t5/fusion-360-ideastation-request-a/pattern-curved-or-straight-lines-in-s...
This one may also be of interest as well.
http://forums.autodesk.com/t5/fusion-360-ideastation-request-a/pattern-work-features/idi-p/5508414
At this time, I note the idea is listed as New Idea. It needs some more votes before it will be moved into the Accepted category. You can learn more about the Ideastation process in the below post.
http://forums.autodesk.com/t5/design-differently/a-better-ideastation-experience-is-coming-soon/ba-p...
I hope this helps. Please let us know if you have any other questions.
Thanks,
Nathan Chandler
Principal Specialist