Yikes, prependToList was violating List immutab...

Yikes, prependToList was violating List immutability. Closes #4656, no
review.

1 files changed, 13 insertions, 0 deletions

diff --git a/test/files/run/bug4656.scala b/test/files/run/bug4656.scala
new file mode 100644
index 0000000000..4f3d189c8f
--- /dev/null
+++ b/test/files/run/bug4656.scala
@@ -0,0 +1,13 @@
+object Test {
+  def f = {
+    val buf = new collection.mutable.ListBuffer[Int]
+    buf ++= List(1, 2, 3)
+    val l = buf.toList
+    buf prependToList List(4, 5, 6)
+    l
+  }
+
+  def main(args: Array[String]): Unit = {
+    println(f)
+  }
+}