breaks as expected, included is the error message

2014-07-15 23:29:37.744 AlertView[1856:60b] Unable to simultaneously satisfy constraints.
	Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
    "<NSLayoutConstraint:0x8f38ec0 H:[UIButton:0x8f39620(22)]>",
    "<NSLayoutConstraint:0x8f39e50 H:|-(NSSpace(20))-[UIButton:0x8f39620]   (Names: '|':UIView:0x8f391e0 )>",
    "<NSLayoutConstraint:0x8f39f00 H:[UIButton:0x8f39620]-(NSSpace(8))-[UILabel:0x8f39790]>",
    "<NSLayoutConstraint:0x8f39f60 H:[UILabel:0x8f39790]-(NSSpace(20))-|   (Names: '|':UIView:0x8f391e0 )>",
    "<NSAutoresizingMaskLayoutConstraint:0x9334600 h=--& v=--& H:[UIView:0x8f391e0(0)]>"
)

Will attempt to recover by breaking constraint
<NSLayoutConstraint:0x8f38ec0 H:[UIButton:0x8f39620(22)]>

Break on objc_exception_throw to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
(lldb)