Merge 3.x into 3.next #443

Job	Run time
cs-stan / Coding Standard & Static Analysis	33s
testsuite / testsuite-linux (8.2, lowest, false)	17s
testsuite / testsuite-linux (8.4, highest, false)	16s
testsuite / testsuite-linux (8.2, highest, false)	20s
testsuite / testsuite-linux (8.5, highest, false)	16s
testsuite / testsuite-linux (8.3, highest, false)	16s
	1m 58s

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