In the Www::Mechanize documents, you see that redirect_ok() is an over loaded method of LWP::UserAgent. If you look LWP::UserAgent docs you will find the following

$ua->redirect_ok( $prospective_request, $response )

    This method is called by request() before it tries to follow a red
+irection to the request in $response. This should return a TRUE value
+ if this redirection is permissible. The $prospective_request will be
+ the request to be sent if this method returns TRUE.

    The base implementation will return FALSE unless the method is in 
+the object's requests_redirectable list, FALSE if the proposed redire
+ction is to a "file://..." URL, and TRUE otherwise.
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Hope this helps!