conversion_create.sql

After upgrading to v 7.3.4 I noticed this error message in the database
setup log:
grep: can't open  <data_path>/conversion_create.sql

Turned out initdb is looking for conversion_create.sql.
We're not building this script and I may need to look into the build
process,
but for now can someone tell me what it does and why we'd need it.

I guess it has to do with locale/data conversion, but there's so much stuff
in
src/backend/utils/mb/conversion_procs that I wonder - do we need to know
which conversions we need to support, or should we build all of them to be
on the safe side?

Thanks,
Mike.