When editing a post, non-hierarchical taxonomy terms are sent as the
comma-separated list entered into the tax_input metabox. Passing these
values directly to `wp_update_post()` meant that they were interpreted as
term slugs rather than term names, causing mismatches when a typed string
matched the slug of one term and the name of a different term. We fix the
problem by preprocessing tax_input data sent from post.php, converting it to
unambiguous term_ids before saving.
Props boonebgorges, ArminBraun.
Fixes#30615.
Built from https://develop.svn.wordpress.org/trunk@31359
git-svn-id: http://core.svn.wordpress.org/trunk@31340 1a063a9b-81f0-0310-95a4-ce76da25c4cd