Use name in env exception

src/library/scala/sys/package.scala

@@ -59,10 +59,17 @@ package object sys {
   //  def prop(p: String) = Option(System.getProperty(p))
 
   /** An immutable Map representing the current system environment.
+   *
+   *  If lookup fails, use `System.getenv(_)` for case-insensitive lookup
+   *  on a certain platform. If that also fails, throw `NoSuchElementException`.
    *
    *  @return   a Map containing the system environment variables.
    */
-  def env: Map[String, String] = Map.from(System.getenv().asScala).withDefault(v => Option(System.getenv(v)).getOrElse(throw new NoSuchElementException))
+  def env: Map[String, String] = Map.from(System.getenv().asScala).withDefault { v =>
+    val s = System.getenv(v)
+    if (s == null) throw new NoSuchElementException(v)
+    s
+  }
 
   /** Register a shutdown hook to be run when the VM exits.
    *  The hook is automatically registered: the returned value can be ignored,

test/junit/scala/sys/env.scala

@@ -14,5 +14,5 @@ class EnvTest {
     if (isWin) assertTrue(sys.env("path") != null)
   }
   @Test def `env throws if not found`(): Unit =
-    assertThrows[NoSuchElementException](sys.env("junk"))
+    assertThrows[NoSuchElementException](sys.env("junk"), _ == "junk")
 }