Fix tag logic in WP_Query::get_queried_object()

[mattonomics]

Currently, the get_queried_object method in WP_Query has logic that correctly accounts for categories and other taxonomies, but not tags.

The attached patch simply includes the very simple logic so that tags may also be properly set up.

[wonderboymusic]

Thanks for the patch - we also need to roll tag vars into tax_query, I will get on that.

[SergeyBiryukov]

Previously: #26627

[wonderboymusic]

In 27511:

In WP_Query::get_queried_object(), account for pre_get_posts by checking for tag when tag_id isn't present. Tags still need to be rolled up into tax_query. Add a unit test confirming expected query vars during and after pre_get_posts.

Props mattonomics for a patch.
See #27362.

[wonderboymusic]

Tags are already slurped up into tax_query, it just never populates query_vars since WP_Query has a member called tax_query. I looked into the redirect_canonical thing: isn't an issue, at all. Not sure where that outburst came from.

[helen]

Reopening, as it's milestoned for 3.8.2.

[nacin]

In [27647]:

In WP_Query::get_queried_object(), account for pre_get_posts by checking for tag when tag_id isn't present.
Merges [27511] to the 3.8 branch.

props mattonomics, wonderboymusic.
fixes #27362.

[bcworkz]

Related #27015. Issues remain using WP_Query::get_queried_object() in 'pre_get_posts' for single posts of any type and author archives.