REST API: Allow a user to change the letter casing of their email.

When a `PUT` request is performed to update a user, a `rest_user_invalid_email` error is incorrectly being returned when the email exists with different letter casing, even if it belongs to the user being updated. `email_exists()` performs a case insensitive lookup, but the conditional statement following that lookup was performing a strict comparison between the new email and the user’s current email.

This changes that comparison to instead compare the user ID returned by `email_exists()` with the user ID being updated. This more closely matches the logic used in `edit_user()` and allows a user to change the letter casing of their email.

Props fuchsws, rachelbaker, desrosj.
Fixes #44672.
Built from https://develop.svn.wordpress.org/trunk@44641


git-svn-id: http://core.svn.wordpress.org/trunk@44472 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php

@@ -641,7 +641,9 @@ class WP_REST_Users_Controller extends WP_REST_Controller {
 			return new WP_Error( 'rest_user_invalid_id', __( 'Invalid user ID.' ), array( 'status' => 404 ) );
 		}
 
-		if ( email_exists( $request['email'] ) && $request['email'] !== $user->user_email ) {
+		$owner_id = email_exists( $request['email'] );
+
+		if ( $owner_id && $owner_id !== $id ) {
 			return new WP_Error( 'rest_user_invalid_email', __( 'Invalid email address.' ), array( 'status' => 400 ) );
 		}
 

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.1-beta1-44640';
+$wp_version = '5.1-beta1-44641';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.