Forward -Dsbt.ivy.home property in scripted tests if set

build.sbt

@@ -1,5 +1,6 @@
 lazy val sbtKotlinPlugin = project.in(file("."))
   .enablePlugins(SbtPlugin)
+  .settings(Scripted.settings)
   .settings(Publishing.settings)
   .settings(
     name         := "sbt-kotlin-plugin",
@@ -9,6 +10,4 @@ lazy val sbtKotlinPlugin = project.in(file("."))
     scalaVersion   := "2.12.17",
     scalacOptions ++= Seq("-deprecation", "-feature", "-Werror", "-Xlint", "-release", "8"),
     javacOptions  ++= Seq("--release", "8"),
-
-    scriptedLaunchOpts += "-Dplugin.version=" + version.value,
   )

project/Scripted.scala

@@ -0,0 +1,19 @@
+import sbt.Def
+import sbt.Keys.version
+import sbt.ScriptedPlugin.autoImport.scriptedLaunchOpts
+
+object Scripted {
+  private val SbtIvyHome = "sbt.ivy.home"
+
+  private val passPluginVersion =
+    scriptedLaunchOpts += "-Dplugin.version=" + version.value
+
+  private val forwardIvyHomeProperty =
+    scriptedLaunchOpts ++= sys.props.get(SbtIvyHome)
+      .map(ivyHome => s"-D$SbtIvyHome=$ivyHome")
+
+  val settings: Seq[Def.Setting[?]] = Seq(
+    passPluginVersion,
+    forwardIvyHomeProperty,
+  )
+}