Use correct user for isUsableBy check in Special:OAuth/identify

The special page's $this->getUser() comes from the normal
CookieSessionProvider cookies (or other non-OAuth mechanism), not the
OAuth headers that are being validated here for use by the /identify
endpoint.

We need to use the user associated with the MWOAuthConsumerAcceptance
instead for proper operation.

Bug: T149194
Change-Id: I0a9f78c4fe7e592a3dbbf084858ba9942a8fac38
(cherry picked from commit 5ec60f469f1cb0520db2710ee25604811d11057b)
1 file changed