identity fn reference of inputKey seems not to reference the expected parser combinator

build.sbt

sbtPlugin := true

name := "input-task-test"

organization := "meh"

version <<= sbtVersion(v => "0.1.0-%s-SNAPSHOT".format(v))

Plugin.scala

package meh

import sbt._
import Keys._

// depend on this in another project
// libraryDependencies  <+= scalaVersion(v => "meh" %% "input-task-test" % "0.1.0-SNAPSHOT")
// try in:input-key foo bar
// then try input-key foo bar
object InputTaskTest extends Plugin {
   val InputConfig = config("in") extend(Runtime)
   val inputKey = InputKey[Unit]("input-key")
   def inputSettings: Seq[Setting[_]] = inConfig(InputConfig)(Seq(
     // binding implementation behavior in `Input` config (the "in" namespace)
     inputKey <<= inputTask { argtask: TaskKey[Seq[String]] =>
       (argtask, streams) map { (args, out) => out.log.info("got %s" format args.mkString) }
     }
   )) ++ Seq(
     // injecting input task key into global scope
     // as an alias to the input task in config
     inputKey <<= (inputKey in InputConfig).identity
   )
}

usage.build.sbt

// include plugin settings
seq(InputTaskTask.inputSettings: _*)

usage.plugins.build.sbt

// resolve plugin
libraryDependencies <+= sbtVersion(v => "meh" %% "test-input-task" % "0.1.0-%s-SNAPSHOT".format(v))

usage.session.log

> in:input-key foo barz
[info] got foobarz
[success] Total time: 0 s, completed Jul 20, 2011 10:06:44 PM

> input-key foo barz   
[error] Parsed result dummy task not found in {file:/Users/dtangren/Desktop/intasktestexample/}default/*:input-key
[error] Use 'last' for the full log.

> last
[info] Set current project to default (in build file:/Users/dtangren/Desktop/intasktestexample/)
[success] Total time: 0 s, completed Jul 20, 2011 10:05:49 PM
[success] Total time: 0 s, completed Jul 20, 2011 10:05:52 PM
java.lang.RuntimeException: Parsed result dummy task not found in {file:/Users/dtangren/Desktop/intasktestexample/}default/*:input-key
	at scala.Predef$.error(Predef.scala:58)
	at sbt.Aggregation$$anonfun$dummyParsedTask$1.apply(Aggregation.scala:153)
	at sbt.Aggregation$$anonfun$dummyParsedTask$1.apply(Aggregation.scala:153)
	at scala.Option.getOrElse(Option.scala:104)
	at sbt.Aggregation$.dummyParsedTask(Aggregation.scala:153)
	at sbt.Aggregation$.sbt$Aggregation$$dummyMap(Aggregation.scala:137)
	at sbt.Aggregation$$anonfun$applyDynamicTasks$1.apply(Aggregation.scala:145)
	at sbt.Aggregation$$anonfun$applyDynamicTasks$1.apply(Aggregation.scala:143)
	at sbt.Command$$anonfun$applyEffect$2$$anonfun$apply$3.apply(Command.scala:63)
	at sbt.Command$$anonfun$applyEffect$2$$anonfun$apply$3.apply(Command.scala:63)
	at sbt.Command$.process(Command.scala:91)
	at sbt.MainLoop$$anonfun$next$1$$anonfun$apply$1.apply(Main.scala:72)
	at sbt.MainLoop$$anonfun$next$1$$anonfun$apply$1.apply(Main.scala:72)
	at sbt.State$$anon$1.process(State.scala:54)
	at sbt.MainLoop$$anonfun$next$1.apply(Main.scala:72)
	at sbt.MainLoop$$anonfun$next$1.apply(Main.scala:72)
	at sbt.ErrorHandling$.wideConvert(ErrorHandling.scala:13)
	at sbt.MainLoop$.next(Main.scala:72)
	at sbt.MainLoop$.run(Main.scala:63)
	at sbt.xMain.run(Main.scala:33)
	at xsbt.boot.Launch$.run(Launch.scala:54)
	at xsbt.boot.Launch$$anonfun$explicit$1.apply(Launch.scala:43)
	at xsbt.boot.Launch$.launch(Launch.scala:68)
	at xsbt.boot.Launch$.apply(Launch.scala:14)
	at xsbt.boot.Boot$.runImpl(Boot.scala:24)
	at xsbt.boot.Boot$.main(Boot.scala:15)
	at xsbt.boot.Boot.main(Boot.scala)

> inspect input-key
[info] Input task
[info] Description:
[info] 	
[info] Provided by:
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}default/*:input-key
[info] Dependencies:
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}default/in:input-key
[info] Delegates:
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}default/*:input-key
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}/*:input-key
[info] 	*/*:input-key
[info] Related:
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}default/in:input-key

> inspect in:input-key
[info] Input task
[info] Description:
[info] 	
[info] Provided by:
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}default/in:input-key
[info] Dependencies:
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}default/in:$parse-result(for input-key)
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}default/in:streams(for input-key)
[info] Reverse dependencies:
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}default/*:input-key
[info] Delegates:
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}default/in:input-key
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}default/*:input-key
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}/in:input-key
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}/*:input-key
[info] 	*/in:input-key
[info] 	*/*:input-key
[info] Related:
[info] 	{file:/Users/dtangren/Desktop/intasktestexample/}default/*:input-key