‘colors’ meta-css src (boolean) generates parse_url errors in _css_href

The admin color stylesheet is a meta stylesheet with the boolean true as the src value. This can lead to invalid urls in Wp_Styles::_css_href when the base url has a port number with 5 digits (10000 and above).

In my case, the home and siteurl values are set to http://localhost:45000/ (the error occurs with and without a trailing slash, it seems this is stripped). Since the value of src is appended to the base url in _css_href, and a boolean true becomes ‘1’ when appended to a string, this results in the src value http://localhost:450001, which leads to errors later in wp_style_loader_src when this temporary url is stripped (by parse_url) to create the actual url.

My solution is to change the default src value of the meta colors stylesheet to false or ‘/’, or some other harmless value.