Make mktmpdir cleanup tolerate missing paths

lib/tmpdir.rb

@@ -73,7 +73,7 @@ def self.tmpdir
   # If a block is given,
   # it is yielded with the path of the directory.
   # The directory and its contents are removed
-  # using FileUtils.remove_entry before Dir.mktmpdir returns.
+  # using FileUtils.remove_entry with force before Dir.mktmpdir returns.
   # The value of the block is returned.
   #
   #  Dir.mktmpdir {|dir|
@@ -111,7 +111,7 @@ def self.mktmpdir(prefix_suffix=nil, *rest, **options, &block)
             raise ArgumentError, "parent directory is world writable but not sticky: #{base}"
           end
         end
-        FileUtils.remove_entry path
+        FileUtils.remove_entry path, true
       end
     else
       path

test/test_tmpdir.rb

@@ -77,6 +77,17 @@ def test_mktmpdir_nil
     }
   end
 
+  def test_mktmpdir_tolerates_removed_directory
+    dir = nil
+    assert_nothing_raised do
+      Dir.mktmpdir do |d|
+        dir = d
+        FileUtils.remove_entry(d)
+      end
+    end
+    assert_file.not_exist?(dir)
+  end
+
   def test_mktmpdir_mutate
     bug16918 = '[ruby-core:98563]'
     assert_nothing_raised(bug16918) do