Add test

Author: som-snytt

tests/warn/i15503a.scala

@@ -213,7 +213,8 @@ package testImportsInImports:
   package c:
     import a.b // OK
     import b.x // OK
-    val y = x
+    import b.x as z // OK
+    val y = x + z
 
 //-------------------------------------
 package testOnOverloadedMethodsImports:
@@ -265,4 +266,4 @@ package foo.test.typeapply.hklamdba.i16680:
     import foo.IO // OK
 
     def f[F[_]]: String = "hello"
-    def go = f[IO]
+    def go = f[IO]