Fix source order sorting. #2162

Job	Run time
minimal	27s
check-cfg	19s
msrv	54s
quickchecking	25s
docs	1m 35s
rustfmt-clippy	31s
test-book	25s
test (ubuntu-latest, 9.0, 1, 0, 0, 0, 0)	1m 49s
test-expectations (ubuntu-latest)	51s
test (ubuntu-latest, 9.0, 1, 0, 0, 1, 0)	2m 46s
test (ubuntu-latest, 9.0, 1, 0, 1, 0, 0)	2m 3s
test-expectations (macos-12)	1m 13s
test (ubuntu-latest, 9.0, 1, 0, 1, 1, 0)	2m 7s
test (ubuntu-latest, 9.0, 1, 1, 0, 0, 0)	3m 5s
test (ubuntu-latest, 9.0, 1, 1, 0, 1, 0)	2m 24s
test (ubuntu-latest, 9.0, 1, 1, 1, 0, 0)	2m 11s
test (ubuntu-latest, 9.0, 1, 1, 1, 1, 0)	2m 20s
test (ubuntu-latest, 16.0, 1, 0, 0, 0, 0)	2m 37s
test (ubuntu-latest, 16.0, 1, 0, 0, 1, 0)	2m 45s
test (ubuntu-latest, 16.0, 1, 0, 1, 0, 0)	2m 42s
test (ubuntu-latest, 16.0, 1, 0, 1, 1, 0)	2m 55s
test (ubuntu-latest, 16.0, 1, 1, 0, 0, 0)	3m 38s
test (ubuntu-latest, 16.0, 1, 1, 0, 1, 0)	3m 6s
test (ubuntu-latest, 16.0, 1, 1, 1, 0, 0)	3m 21s
test (ubuntu-latest, 16.0, 1, 1, 1, 1, 0)	3m 25s
test (ubuntu-latest, 16.0, 0, 0, 1)	1m 43s
test (macos-12, 9.0, 0, 0, 0)	1m 26s
success	1s
	53m 4s

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