WordPress 4.4 fatal error with this theme

WordPress 4.4 function get_the_post_thumbnail_url() found in theme file functions.php conflicts with a core function now found in:

Conflicting function name: get_the_post_thumbnail_url()
WordPress core file: ./wp-includes/post-thumbnail-template.php
Your theme file: ./wp-content/themes/sliding-door/functions.php

I simply renamed it and upgraded the site to WordPress 4.4

While awaiting a fix from the theme author, simply changing the name of the function to get_the_post_thumbnail_url1() and changing the two references as follows

3 changes to sliding-door/functions.php :

function name: line 211
function call: line 246
function call: line 270

choose a non-conflicting function name, like sliding_theme_get_the_post_thumbnail_url()