This was added in 2013, in 11d8cdef6f -- and referenced that Django
did not use the setting, but South did. Zulip stopped using South a
decade ago (599742536b).
A later 2013 commit, 94c61f5507 said:
Currently our test database is backed by sqlite; this commit moves
us to using postgres for our all database needs. This, in conjunction
with the patched django on github, allow us to have fewer hacks and
more true-to-life tests. It also sets the stage for testing the
bulk_create and schema search_path patches made to django.
The "patched django" and "schema search_path patches" is a reference
to a 2013 branch in Zulip's now-archived fork of Django[^1]. These
patches were never merged into mainline Django (and other similar
unsuccessful efforts in Django go back even farther[^2], to 2007).
The setting was only ever read in pgroonga migrations which attempted
to undo other migrations; remove it, hardcoding "zulip" where
necessary to replace it. The schema which Zulip uses (for queries,
and creating new objects) is controlled by the `search_path` setting
for the connection, or from the user.
[^1]: https://github.com/django/django/compare/1.5.4...zulip:django:acrefoot-bulk_create_and_postgres_schemas-1.5.4
[^2]: https://code.djangoproject.com/ticket/6148
f0977a046f