Add specs for [Bug #20654] #1722

Job	Run time
RuboCop	26s
specs (ubuntu, 3.0.6)	1m 29s
specs (ubuntu, 3.1.4)	1m 30s
specs (ubuntu, 3.2.2)	1m 23s
specs (ubuntu, 3.3.0)	1m 21s
specs (macos, 3.0.6)	1m 17s
specs (macos, 3.1.4)	1m 27s
specs (macos, 3.2.2)	1m 9s
specs (macos, 3.3.0)	1m 18s
specs (windows, 3.0.6)	4m 12s
specs (windows, 3.1.4)	4m 3s
specs (windows, 3.2.2)	4m 42s
specs (windows, 3.3.0)	5m 6s
specs (ubuntu, 3.3.0, --enable-frozen-string-literal)	1m 23s
	30m 46s

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