Administration: Restore the full-width upload folder row on Settings > Media

[dknauss]

Trac ticket: https://core.trac.wordpress.org/ticket/51190

Problem

On Settings > Media, "Organize my uploads into month- and year-based folders" wraps onto three lines as soon as any plugin registers a field in the uploads settings section.

Cause

The row spanned both columns unconditionally until [40823] (#37004, HTML validation fixes) moved it inside the upload-path conditional in order to change its th to a td. That carried colspan="2" onto the editable-paths branch only:

<tr>
<td colspan="2" class="td-full">
<?php else : ?>
<tr>
<td class="td-full">
<?php endif; ?>

The else branch is what a site with default upload paths gets. With no fields registered the table has one column and the cell fills it, so nothing looks wrong. The do_settings_fields( 'media', 'uploads' ) call on the next line invites a second column, and once anything takes it, .form-table th { width: 200px } claims the first and the core label wraps.

forms.css dates the change from the other side: .form-table th.th-full, /* Not used by core. Back-compat for pre-4.8 */.

Fix

Close the conditional above the row and restore the single unconditional cell, keeping the td/td-full markup [40823] introduced.

Measured at a 1238px content width:

	cell width	label height
no plugin fields, no colspan (trunk)	1238px	17px
no plugin fields, colspan="2"	1238px	17px
one plugin field, no colspan (trunk)	210px	55px
one plugin field, colspan="2"	1238px	17px

The first two rows are identical because colspan="2" on a lone cell in a one-column table spans what it already spanned, so no check for registered fields is needed and rendering is unchanged for sites without them.

Testing instructions

1. Make sure upload_path and upload_url_path are at their defaults, so the paths are locked (the common case).
2. Visit Settings > Media and confirm the checkbox is on one line.
3. Drop this in wp-content/mu-plugins/:

<?php
add_action( 'admin_init', function () {
	add_settings_field(
		'demo_field',
		'Demo Field',
		function () {
			echo '<input type="text" class="regular-text">';
		},
		'media',
		'uploads'
	);
} );

4. Reload Settings > Media. On trunk the checkbox label wraps onto three lines in a 200px column; with this change it stays on one line and the new field renders below it.

Props imath for the report and diagnosis.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

Core Committers: Use this line as a base for the props when committing in SVN:

Props dpknauss.

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[github-actions]

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[dknauss]

The props line above credits only me. imath reported this on #51190, worked out the cause, and attached the first patch — this PR takes a different route to the same fix, but the diagnosis is theirs.

For SVN:

Props imath, dpknauss.