 			return
 		}
 
-		launchGitTask([ "rev-parse", "\(revision)^{commit}" ], repositoryFileURL: repositoryFileURL, standardOutput: SinkOf<NSData> { _ in () }, standardError: SinkOf<NSData> { _ in () })
+		launchGitTask([ "rev-parse", "\(revision)^{commit}" ], repositoryFileURL: repositoryFileURL)
 			|> then(SignalProducer<Bool, CarthageError>(value: true))
 			|> catch { _ in SignalProducer<Bool, NoError>(value: false) }
 			|> startWithSignal { signal, signalDisposable in

	let modulesObject = "\(revision):.gitmodules"
	let baseArguments = [ "config", "--blob", modulesObject, "-z" ]

	return launchGitTask(baseArguments + [ "--get-regexp", "submodule\\..*\\.path" ], repositoryFileURL: repositoryFileURL, standardError: SinkOf<NSData> { _ in () })
		|> catch { _ in SignalProducer<String, NoError>.empty }
		|> flatMap(.Concat) { value in parseConfigEntries(value, keyPrefix: "submodule.", keySuffix: ".path") }
		|> promoteErrors(CarthageError.self)

/// the path could not be loaded.
public func contentsOfFileInRepository(repositoryFileURL: NSURL, path: String, revision: String = "HEAD") -> SignalProducer<String, CarthageError> {
	let showObject = "\(revision):\(path)"
	return launchGitTask([ "show", showObject ], repositoryFileURL: repositoryFileURL)
}

/// Checks out the working tree of the given (ideally bare) repository, at the
