Comment (by Zach Etienne):

Again I cannot reproduce the problems you are seeing. Before reporting this problem again, first confirm that you can reproduce from a connection that is completely free from firewalls. I’d suggest creating a tarball from that connection and using that version from the firewalled connection.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2535/et_2020_11-build-issue