Handle $_POST containing an empty term array, Fixes saving of deselecting all hierarchical terms. Fixes #10122

git-svn-id: http://svn.automattic.com/wordpress/trunk@14426 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/meta-boxes.php

@@ -307,6 +307,10 @@ function post_categories_meta_box( $post, $box ) {
 		</div>
 
 		<div id="<?php echo $taxonomy; ?>-all" class="tabs-panel">
+			<?php
+            $name = ( $taxonomy == 'category' ) ? 'post_category' : 'tax_input[' . $taxonomy . ']';
+            echo "<input type='hidden' name='{$name}[]' value='0' />"; // Allows for an empty term set to be sent. 0 is an invalid Term ID and will be ignored by empty() checks.
+            ?>
 			<ul id="<?php echo $taxonomy; ?>checklist" class="list:<?php echo $taxonomy?> categorychecklist form-no-clear">
 				<?php wp_terms_checklist($post->ID, array( 'taxonomy' => $taxonomy, 'popular_cats' => $popular_ids ) ) ?>
 			</ul>