Gutenberg page omits hreflang tags

[jonoaldersonwp]

Gutenberg pages, like ​https://ary.wordpress.org/gutenberg/, omit hreflang tagging.

As per other templates, a matrix of hreflang equivalents should be generated and output.

[diddledani]

The hreflang output in the rest of the W.org site is handled by https://meta.trac.wordpress.org/browser/sites/trunk/wordpress.org/public_html/wp-content/themes/pub/wporg/functions.php#L192. I'm unsure whether copying this code into either a shared location to be called from both wporg theme and gutentheme, or into the gutentheme directly will be suitable to fix this issue.

The Gutenberg section is actually a separate multisite blog so I'm not certain that the same localisation will work in both places. The WordPress-meta-environment in VVV isn't helping me here because it doesn't know about the Gutenberg site.