Skip a new spec for Dir#chdir on Windows when original directory is r… #1895

Job	Run time
RuboCop	34s
specs (ubuntu, 3.0.6)	1m 37s
specs (ubuntu, 3.1.4)	1m 33s
specs (ubuntu, 3.2.2)	1m 28s
specs (ubuntu, 3.3.0)	1m 27s
specs (ubuntu, 3.4.1)	1m 33s
specs (macos, 3.0.6)	1m 32s
specs (macos, 3.1.4)	1m 31s
specs (macos, 3.2.2)	1m 13s
specs (macos, 3.3.0)	1m 14s
specs (macos, 3.4.1)	1m 23s
specs (windows, 3.0.6)	3m 22s
specs (windows, 3.1.4)	4m 57s
specs (windows, 3.2.2)	5m 31s
specs (windows, 3.3.0)	3m 55s
specs (windows, 3.4.1)	5m 18s
specs (ubuntu, 3.3.0, --enable-frozen-string-literal)	1m 27s
	39m 35s

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