pathmapper: don't use temporary lists #1918

Job	Run time
CWL conformance (v1.0, docker)	3m 32s
Linters (lintreadme)	57s
CWL conformance (v1.0, singularity)	3m 24s
No leftovers	15m 9s
CWL conformance (v1.0, podman)	3m 38s
Linters (shellcheck)	11s
Tox (3, 8, lint)	29s
CWL conformance (v1.1, docker)	4m 51s
Linters (pydocstyle)	15s
Tox (3, 8, unit)	7m 18s
Tox (3, 8, bandit)	28s
CWL conformance (v1.1, singularity)	6m 26s
build_test_container	15m 7s
Tox (3, 8, mypy)	7m 28s
CWL conformance (v1.1, podman)	5m 3s
Tox (3, 9, lint)	28s
CWL conformance (v1.2, docker)	6m 12s
Test on macos-latest	14m 59s
CWL conformance (v1.2, singularity)	7m 24s
Tox (3, 9, unit)	6m 28s
CWL conformance (v1.2, podman)	6m 51s
cwltool release test	15m 8s
Tox (3, 9, bandit)	31s
CWL conformance (v1.2, docker, --fast-parser)	6m 17s
Tox (3, 9, mypy)	6m 40s
Tox (3, 10, lint)	30s
Tox (3, 10, unit)	9m 58s
Tox (3, 10, bandit)	26s
Tox (3, 10, mypy)	10m 16s
Tox (3, 11, lint)	26s
Tox (3, 11, unit)	8m 30s
Tox (3, 11, bandit)	24s
Tox (3, 11, mypy)	9m 54s
Tox (3, 12, lint)	34s
Tox (3, 12, unit)	8m 7s
Tox (3, 12, bandit)	35s
Tox (3, 12, mypy)	8m 18s
	3h 23m 12s

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