Fix a rare issue with same-host restriction causing updates to fail.
Fix a rare issue with same-host restriction causing updates to fail.

WordPress has a security feature where the HTTP API will reject all requests that are sent to another site hosted on the same server as the current site (IP match) or a local host/IP, unless the host exactly matches the current site. This feature is opt-in, but apparently some people (or security plugins?) enable it.

This can be a problem when the update metadata is on the same server as your site, but not on the exact same hostname. The aforementioned security restriction will cause updates to fail for no apparent reason.

The patch fixes the issue by using the "http_request_host_is_external" filter to explicitly allow the host that the metadata URL points to.
YahnisElsts/plugin-update-checker,YahnisElsts/plugin-update-checker