In the past 2 days the isabelle_cronjob could not connect to
https://isabelle.in.tum.de/repos/isabelle -- but it appears to work from
most other hosts that I've tried. Maybe some odd change concerning SSL
certificates on the server vs. client side?
To keep the release process going, I've now set up clones of the
relevant repositories that are synchronized via ssh every 10 min:
https://isabelle.sketis.net/repos -- see also Isabelle/7538b5f301ea.
That was very easy following
https://www.mercurial-scm.org/wiki/PublishingRepositories and I am
inclined to give up https://bitbucket.org/isabelle_project eventually,
and use https://isabelle.sketis.net/repos instead. It is generally
better to stand on ones own feet, instead requiring the handholding of
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