Use proxyInputStream instead of wrappedSystemIn

I'm not sure why the scala.Console.withIn was using proxyInputStream
while the other input streams were set to wrapedSystemIn. At any rate,
using the wrappedSystemIn would likely prevent reading input from
working with the thin client.

internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala

@@ -518,8 +518,8 @@ object Terminal {
   }
   private[this] def withIn[T](f: => T): T =
     try {
-      inputStream.set(Terminal.wrappedSystemIn)
-      System.setIn(wrappedSystemIn)
+      inputStream.set(proxyInputStream)
+      System.setIn(proxyInputStream)
       scala.Console.withIn(proxyInputStream)(f)
     } finally System.setIn(originalIn)