authority.simple_heading_set and differing joiners

[Mackenzie Johnson]

EG 3.8.0 (though I believe it would also affect the main branch)
PostgreSQL 10.something

By default, when running authority.simple_heading_set and populating authority.simple_heading, authority fields that have a linked value to authority.heading_field (ie. 1XX, 4XX, and 5XX main headings) are first parsed through authority.extract_headings, while other headings (namely 7XX linking entry headings) are parsed through the alternate methods established in the simple_heading_set function itself. By default, this can create a discrepancy in punctuation, as authority.extract_headings uses the joiner stored in authority.heading_field, while simple_heading_set otherwise uses the joiner stored in authority.control_set_authority_field. A simple enough fix at the local level by means of updating the joiners, but to match the joiners out of the box would be useful for some consistency.

All that being said, there may need to be some further consideration about the default joiners used when considering name parts, but that may not be as concerning of an issue given normalization functions.