For storyboards we can set the "Builds for" value in the file inspector of Interface Builder. There is a default value, supposedly corresponding to my deployment target, which is not correct in my case (It does not correspond to my minimum deployment target, which is 11.0. Instead I get 10.3). This prevents my app from building, because the storyboard is not compatible with this build target.
(I can't set it manually and be done with it, because the storyboard is recreated by a script every time a clean build is run.)
(I can't set it manually and be done with it, because the storyboard is recreated by a script every time a clean build is run.)