Ruby

Add information for VariableDuplicationError #6252

Job	Run time
test (3.1, test)	2m 13s
test (3.2, test)	2m 0s
test (3.3, test)	2m 24s
test (3.4, test)	2m 19s
test (head, test)	2m 12s
test (head, stdlib_test rubocop)	1m 54s
test (3.4, stdlib_test)	1m 42s
test (3.4, test, --enable-frozen-string-literal)	2m 17s
test (3.4, stdlib_test, --enable-frozen-string-literal)	1m 45s
test (3.4, lexer templates compile confirm_lexer confirm_templates)	3m 15s
test (3.4, rubocop validate test_doc build test_generate_stdlib raap)	2m 8s
test (3.4, typecheck_test)	53s
	25m 2s

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