UIStackView can't be used when the deployment target is lower than 9.0 and Cocoapods version is 1.1.0.rc3

When I update Cocoapods to 1.1.0.rc3
It seems the verifying is more strict in CocoaPods

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ibtool --reference-external-strings-file --errors --warnings --notices --minimum-deployment-target 7.0 --output-format human-readable-text --compile /Users/jenkins/Library/Developer/Xcode/DerivedData/EMStock-ejggipzgbvudbrelswbgumssqjfg/Build/Products/Debug-iphonesimulator/EMStock.app/EMIndDetailCell.nib /Users/jenkins/Desktop/emstock-git@pod1.0/Pods/EMMarket/EMMarket/StockDetail/Classes/view/EMIndDetailCell.xib --sdk /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator10.0.sdk --target-device iphone