[35333] implemented `public=false` for taxonomies. The implementation prevented
non-public taxonomies from having their archives accessed via query_var during
a normal request. But it didn't prevent non-public taxonomies from registering
their query vars in the `$wp_taxonomies` global. The latter implementation
details causes problems specifically when a taxonomy is registered with
`query_var=true`; for public taxonomies, `register_taxonomy()` translates this
into a query_var equivalent to the taxonomy name, but in the case of non-public
taxonomies, the query_var was set to the boolean itself. The boolean then
causes problems when using non-strict comparison to filter taxonomy objects by
query_var, as when using `get_taxonomies()`.
This changeset addresses the issue by forcing the query_var property of
non-public taxonomies to `false`.
Merges [36108] to the 4.4 branch.
Fixes#35089.
git-svn-id: https://develop.svn.wordpress.org/branches/4.4@36109 602fd350-edb4-49c9-b593-d223f7449a82
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