Customize: Fix logic inversion in determining whether a URL is previewable which prevented previewing anything but homepage.

Fixes regression introduced in [38890].

See #38409.
Fixes #38492.

Built from https://develop.svn.wordpress.org/trunk@38926


git-svn-id: http://core.svn.wordpress.org/trunk@38869 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/customize-controls.js

@@ -4173,7 +4173,7 @@
 				_.find( parsedCandidateUrls, function( parsedCandidateUrl ) {
 					return ! _.isUndefined( _.find( previewer.allowedUrls, function( allowedUrl ) {
 						parsedAllowedUrl.href = allowedUrl;
-						if ( urlParser.protocol === parsedAllowedUrl.protocol && urlParser.host === parsedAllowedUrl.host && 0 === parsedAllowedUrl.pathname.indexOf( urlParser.pathname ) ) {
+						if ( urlParser.protocol === parsedAllowedUrl.protocol && urlParser.host === parsedAllowedUrl.host && 0 === urlParser.pathname.indexOf( parsedAllowedUrl.pathname.replace( /\/$/, '' ) ) ) {
 							result = parsedCandidateUrl.href;
 							return true;
 						}