posts_per_page causing infinite duplicate content

[firebird75]

While using the posts_per_page in the pre_get_posts, if you set it to -1. It will output all the posts. The issue is that if you use this with the main query on a taxonomy archive page, then it will create unlimited number of subpages with all the same content as the main page :
taxonomy-1/
taxonomy-1/page/2/
taxonomy-1/page/3/
...
taxonomy-1/page/500/
etc...

It is probably not really the expected behavior...

[SergeyBiryukov]

Related: #11694, #28081, #29655.

[tyxla]

The same applies to all other types of archive pages - year, month, day, author.

1. Paging block: new elseif - when nopaging is truthy, not singular, and paged > 1, set $limits = 'LIMIT 0'. The query returns zero rows instead of the full result set on every paginated URL.
2. set_found_posts(): when $limits is non-empty and nopaging is truthy, max_num_pages = 1 (posts_per_page is -1 there and can't divide the total).

Trac ticket: https://core.trac.wordpress.org/ticket/30631

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