Fix source order sorting. #1745

Job	Run time
rustfmt-clippy	55s
minimal	26s
docs	26s
check-cfg	30s
quickchecking	27s
msrv	4m 53s
test-book	15s
test-expectations (ubuntu-latest)	1m 39s
test (ubuntu-latest, 5.0, 1, 0, 0, 0, 0)	2m 54s
test-expectations (macos-latest)	3m 52s
test (ubuntu-latest, 5.0, 1, 0, 0, 1, 0)	2m 53s
test (ubuntu-latest, 5.0, 1, 0, 1, 0, 0)	2m 49s
test (ubuntu-latest, 5.0, 1, 0, 1, 1, 0)	2m 44s
test (ubuntu-latest, 5.0, 1, 1, 0, 0, 0)	2m 52s
test (ubuntu-latest, 5.0, 1, 1, 0, 1, 0)	2m 52s
test (ubuntu-latest, 5.0, 1, 1, 1, 0, 0)	2m 50s
test (ubuntu-latest, 5.0, 1, 1, 1, 1, 0)	2m 51s
test (ubuntu-latest, 9.0, 1, 0, 0, 0, 0)	2m 34s
test (ubuntu-latest, 9.0, 1, 0, 0, 1, 0)	2m 49s
test (ubuntu-latest, 9.0, 1, 0, 1, 0, 0)	2m 45s
test (ubuntu-latest, 9.0, 1, 0, 1, 1, 0)	2m 50s
test (ubuntu-latest, 9.0, 1, 1, 0, 0, 0)	2m 54s
test (ubuntu-latest, 9.0, 1, 1, 0, 1, 0)	2m 54s
test (ubuntu-latest, 9.0, 1, 1, 1, 0, 0)	2m 51s
test (ubuntu-latest, 9.0, 1, 1, 1, 1, 0)	2m 52s
test (ubuntu-latest, 9.0, 0, 0, 1)	1m 40s
test (macos-latest, 9.0, 0, 0, 0)	2m 30s
	1h 2m 47s

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