Unable to override setting from extra project

[steinybot]

steps

project/HammerPlugin.scala:

import sbt._

object HammerPlugin extends AutoPlugin {

  object autoImport {

    val cantTouchThis = settingKey[String]("Override this if you can.")
  }

  import autoImport._

  private val mcProject = Project("mc", file("."))
    .configure(p => p.in(file("target") / "dynamic-projects" / p.id))
    .settings(cantTouchThis := "Can't touch this!")

  override def extraProjects: Seq[Project] = Seq(mcProject)
}

build.sbt

enablePlugins(PrayPlugin)

cantTouchThis in LocalProject("mc") := "This doesn't work."

sbt:

sbt:bug-reports> show mc/cantTouchThis
[info] Can't touch this!

problem

All the normal ways of overriding settings do not seem to work on projects from plugins that are added via extraProjects.

expectation

sbt:

sbt:bug-reports> show mc/cantTouchThis
[info] This doesn't work.

notes

There is a reproduction with a few other things that I have tried in https://github.com/steinybot/bug-reports/tree/sbt/extra-project-settings.

[steinybot]

This works around the problem:

lazy val updateExtraProject: State => State = { s: State =>
  val projectID = "mc"
  val value = "Finally!"
  if (Project.extract(s).get(LocalProject(projectID) / cantTouchThis) == value)
    s
  else s"""set (LocalProject("$projectID") / cantTouchThis) := "$value"""" :: s
}

Global / onLoad := {
  val old = (Global / onLoad).value
  updateExtraProject compose old
}

[eed3si9n]

I'm guessing it's something to do with Load.scala

sbt/main/src/main/scala/sbt/internal/Load.scala

Line 700 in 6dff457

val initialProjects = defsScala.flatMap(b => projectsFromBuild(b, normBase)) ++ buildLevelExtraProjects

Maybe you could try flipping the order in the above.

[steinybot]

That didn't seem to make any difference.

I also noticed that extra projects are added to the build even if the plugin is not enabled on any other project.