API Requests sometimes lose body

[granthony]

In limited circumstances, HTTP requests made using wp-includes/Requests/src/Requests.php will incorrectly return an empty string as the response body, even though the request executed and returned a value in the response.

This happens when the returned value is PHP-falsey (for example, the string "0") - or in other words, when empty($value) evaluates to true in PHP.

I've encountered this issue in production, so the diff we went with is attached.

[granthony]

Patch for WP::Requests class to handle '0' response body

[mindctrl]

I think patches for Requests go in the upstream library here: ​https://github.com/WordPress/Requests

[sabernhardt]

(See ​line 742 on the GitHub repository if you want to create a pull request.)

The substr() function should always ​return a string. I think simply checking for an empty string would suffice:
if ($body !== '')

[sabernhardt]

Apparently I was wrong about returning a string (in all versions of PHP), but the pull request is on GitHub for further discussion:
​https://github.com/WordPress/Requests/pull/933