Fix source order sorting. #1746

Job	Run time
minimal	21s
docs	28s
check-cfg	33s
msrv	5m 27s
quickchecking	31s
rustfmt-clippy	51s
test-book	7s
test (ubuntu-latest, 5.0, 1, 0, 0, 0, 0)	2m 59s
test-expectations (ubuntu-latest)	1m 39s
test (ubuntu-latest, 5.0, 1, 0, 0, 1, 0)	3m 28s
test-expectations (macos-latest)	3m 53s
test (ubuntu-latest, 5.0, 1, 0, 1, 0, 0)	3m 16s
test (ubuntu-latest, 5.0, 1, 0, 1, 1, 0)	3m 39s
test (ubuntu-latest, 5.0, 1, 1, 0, 0, 0)	3m 27s
test (ubuntu-latest, 5.0, 1, 1, 0, 1, 0)	4m 15s
test (ubuntu-latest, 5.0, 1, 1, 1, 0, 0)	4m 27s
test (ubuntu-latest, 5.0, 1, 1, 1, 1, 0)	3m 16s
test (ubuntu-latest, 9.0, 1, 0, 0, 0, 0)	2m 50s
test (ubuntu-latest, 9.0, 1, 0, 0, 1, 0)	2m 57s
test (ubuntu-latest, 9.0, 1, 0, 1, 0, 0)	4m 0s
test (ubuntu-latest, 9.0, 1, 0, 1, 1, 0)	3m 42s
test (ubuntu-latest, 9.0, 1, 1, 0, 0, 0)	3m 52s
test (ubuntu-latest, 9.0, 1, 1, 0, 1, 0)	4m 24s
test (ubuntu-latest, 9.0, 1, 1, 1, 0, 0)	4m 5s
test (ubuntu-latest, 9.0, 1, 1, 1, 1, 0)	5m 28s
test (ubuntu-latest, 9.0, 0, 0, 1)	2m 8s
test (macos-latest, 9.0, 0, 0, 0)	1m 27s
	1h 17m 30s

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