[ruby/pathname] Raise the previous message

Fix ruby/pathname#75.

ruby/pathname@5ba967b274

Author: nobu

pathname_builtin.rb

@@ -213,6 +213,8 @@ class Pathname
   #
   def initialize(path)
     @path = File.path(path).dup
+  rescue TypeError => e
+    raise e.class, "Pathname.new requires a String, #to_path or #to_str", cause: nil
   end
 
   #

test/pathname/test_pathname.rb

@@ -486,7 +486,7 @@ def test_initialize
     assert_equal(p1, p2)
 
     obj = Object.new
-    assert_raise(TypeError) { Pathname.new(obj) }
+    assert_raise_with_message(TypeError, /#to_path or #to_str/) { Pathname.new(obj) }
 
     obj = Object.new
     def obj.to_path; "a/path"; end