Factor out common bits of informativeUsageError()
Factor out common bits of informativeUsageError()

erichoracek/Carthage,NachoSoto/Carthage,erichoracek/Carthage,abbeycode/Carthage,0xced/Carthage,abbeycode/Carthage,flovilmart/Carthage,abbeycode/Carthage,0xced/Carthage,flovilmart/Carthage,NachoSoto/Carthage,0xced/Carthage,abbeycode/Carthage,NachoSoto/Carthage,erichoracek/Carthage,erichoracek/Carthage,flovilmart/Carthage