The option -m foo.th does not work (nor its variant -m=foo.th), but --master=foo.th does work. The usage message says the code was written by Ian Kelly. One of the default locations checked for the MasterThornList should be ./repos/manifest/einsteintoolkit.th, and multiple par files (or a directory containing par files) should probably be accepted.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2439/makethornlist-issues