Fixes #1439. Fixes metabuild downloading unused Scala 2.10.2

Scala instance is added to the Ivy graph via autoLibraryDependency.
For metabuilds, scala-library is scoped under “provided” configuration,
which does not seem to evict modules on “compiled” configuration.
This commit turns overrideScalaVersion flag to true for the metabuilds,
so override rules are added for the following modules:
- scala-library
- scala-compiler
- scala-reflect

ivy/src/main/scala/sbt/IvyScala.scala

@@ -16,6 +16,7 @@ object ScalaArtifacts {
   val Organization = ScalaOrganization
   val LibraryID = ScalaLibraryID
   val CompilerID = ScalaCompilerID
+  val ReflectID = "scala-reflect"
   def libraryDependency(version: String): ModuleID = ModuleID(Organization, LibraryID, version)
 
   private[sbt] def toolDependencies(org: String, version: String): Seq[ModuleID] = Seq(
@@ -47,6 +48,7 @@ private object IvyScala {
   def overrideScalaVersion(module: DefaultModuleDescriptor, version: String) {
     overrideVersion(module, Organization, LibraryID, version)
     overrideVersion(module, Organization, CompilerID, version)
+    overrideVersion(module, Organization, ReflectID, version)
   }
   def overrideVersion(module: DefaultModuleDescriptor, org: String, name: String, version: String) {
     val id = new ModuleId(org, name)

main/src/main/scala/sbt/Defaults.scala

@@ -1070,8 +1070,8 @@ object Classpaths {
     allDependencies := {
       projectDependencies.value ++ libraryDependencies.value
     },
-    ivyScala <<= ivyScala or (scalaHome, scalaVersion in update, scalaBinaryVersion in update, scalaOrganization) { (sh, fv, bv, so) =>
-      Some(new IvyScala(fv, bv, Nil, filterImplicit = false, checkExplicit = true, overrideScalaVersion = false, scalaOrganization = so))
+    ivyScala <<= ivyScala or (scalaHome, scalaVersion in update, scalaBinaryVersion in update, scalaOrganization, sbtPlugin) { (sh, fv, bv, so, plugin) =>
+      Some(new IvyScala(fv, bv, Nil, filterImplicit = false, checkExplicit = true, overrideScalaVersion = plugin, scalaOrganization = so))
     },
     artifactPath in makePom <<= artifactPathSetting(artifact in makePom),
     publishArtifact in makePom := publishMavenStyle.value && publishArtifact.value,

notes/0.13.6.md

@@ -31,6 +31,7 @@
   [1423]: https://github.com/sbt/sbt/pull/1423
   [1426]: https://github.com/sbt/sbt/pull/1426
   [1433]: https://github.com/sbt/sbt/pull/1433
+  [1439]: https://github.com/sbt/sbt/issues/1439
   [1447]: https://github.com/sbt/sbt/pull/1447
   [1450]: https://github.com/sbt/sbt/pull/1450
   [1451]: https://github.com/sbt/sbt/pull/1451
@@ -112,6 +113,7 @@
 - Fixes config-classes leak in loading build files. [#1524][1524] by [@jsuereth][@jsuereth]
 - Fixes name-conflicts in hashed settings class files. [#1465][1465] by [@jsuereth][@jsuereth]
 - Fixes `NullPointerError` in tab completion by `FileExamples`. [#1530][1530] by [@eed3si9n][@eed3si9n]
+- Fixes metabuild downloading unused Scala 2.10.2. [#1439][1439] by [@eed3si9n][@eed3si9n]
 
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