[ruby/pp] Fix pretty printing a Data subclass instance when the subclass is anonymous

* It would be "#<data  a=42>" (double space) instead of "#<data a=42>" (like #inspect).

https://github.com/ruby/pp/commit/bed72bfcb8

lib/pp.rb

@@ -422,7 +422,9 @@ end
 
 class Data # :nodoc:
   def pretty_print(q) # :nodoc:
-    q.group(1, sprintf("#<data %s", PP.mcall(self, Kernel, :class).name), '>') {
+    class_name = PP.mcall(self, Kernel, :class).name
+    class_name = " #{class_name}" if class_name
+    q.group(1, "#<data#{class_name}", '>') {
       q.seplist(PP.mcall(self, Kernel, :class).members, lambda { q.text "," }) {|member|
         q.breakable
         q.text member.to_s

test/test_pp.rb

@@ -149,6 +149,9 @@ class PPCycleTest < Test::Unit::TestCase
       a = D.new("aaa", "bbb")
       assert_equal("#<data PPTestModule::PPCycleTest::D\n aaa=\"aaa\",\n bbb=\"bbb\">\n", PP.pp(a, ''.dup, 20))
       assert_equal("#{a.inspect}\n", PP.pp(a, ''.dup))
+
+      b = Data.define(:a).new(42)
+      assert_equal("#{b.inspect}\n", PP.pp(b, ''.dup))
     end
   end