As useful as the custom jhbuild setup was at the time, it has been
superseded by jhbuild proper (which gained the ability to install
system dependencies since) or alternatives like containers.
Given that the script hasn't been meaningfully updated for almost
10 years, its list of dependencies is hopelessly outdated, and it's
therefore more likely to confuse newcomers than being of actual
help.
As much as I have fond memories of the script when starting out,
it's finally time to retire.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3040>
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