[BUG] nginx 0.8.42 disables IO interruption capability completely in the whole rewrite phase and breaks many modules

[agentzh]

Hi, all

nginx 0.8.42 introduces a patch that explicitly ignore NGX_AGAIN and
NGX_DONE return values from *any* rewrite phase handlers and breaks
lots of interesting modules like ngx_eval and my ngx_form_input,
ngx_srcache, as well as ngx_chunkin.

Even though the access phase handlers can still return NGX_AGAIN or
NGX_DONE to do non-blocking I/O stuffs, but it always runs after all
the rewrite phase commands and is always skipped completely in
subrequests, so not very interesting at all for developers.

Is this an intentional design decision or just an unintentional regression?

Cheers,
-agentzh