Hmm downgrading to 3.6.1 seems to resolve the issue…
Found the answer. It was caused by a plugin in mu-plugins folder…
Thanks for your answer. There is no robots.txt file in that folder, or in any folder.
@plesin, thanks! That worked for me. Hopefully this issue will be addressed in an update. There must be a WordPress tag/function to get the right site url right?
