Unscoped task does not work when another AutoPlugin declares projectConfigurations

[pelepelin]

Expected vs Actual Behaviour

It should...

Both jacoco and test:jacoco should work.

Instead it...

> jacoco
[error] Not a valid command: jacoco
[error] Not a valid project ID: jacoco (similar: double-jacoco)
[error] Expected ':' (if selecting a configuration)
[error] Ambiguous keys: test:jacoco, test:jacoco
[error] jacoco
[error]       ^
> test:jacoco
[info] Instrumenting 0 classes to C:\dev\java\tmp\double-jacoco\target\scala-2.12\jacoco\instrumented-
... skip ...
[success] Total time: 0 s, completed 22.01.2018 22:09:39

Steps to Reproduce

build.sbt

enablePlugins(MyPlugin)
scalaVersion := "2.12.4"

project/MyPlugin.scala

import sbt._
object MyPlugin extends AutoPlugin {
  override def projectConfigurations = Seq(Test)
}

project/build.properties

sbt.version = 0.13.16

project/plugins.sbt

addSbtPlugin("com.github.sbt" % "sbt-jacoco" % "3.0.3")

Environment

• SBT version: 0.13.16
• Plugin version: 3.0.3
• Scala version(s): 2.12.4
• Java version:
  java version "1.8.0_131"
  Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
  Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)

Side note: each plugin should declare which configurations it uses by overriding projectConfigurations, but this apparently does not fix the problem.