test_fileutils.rb: fix test

* test/fileutils/test_fileutils.rb (test_chown_error): splat uids.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44388 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/fileutils/test_fileutils.rb

@@ -1123,7 +1123,7 @@ class TestFileUtils < Test::Unit::TestCase
 
   if have_file_perm?
     def test_chown_error
-      uid = distinct_uids(1)
+      uid, = distinct_uids(1)
       return unless uid
 
       touch 'tmp/a'