* prevent regressions of #5082
* Fix test_leauto_upgrades.sh
test_leauto_upgrades.sh has been incorrectly been succeeding because while peep
doesn't work with newer versions of pip and letsencrypt-auto would crash,
the output included the version number so we reported the test as passing.
This updates letsencrypt-auto to the oldest version that still works for the
purpose of the test and sets pipefail so errors are properly reported.
* Test symlink creation in test_leauto_upgrades.sh
* Pin dependencies in test_sdists.sh.
* Fix permissions errors in test_tests.sh
