Fix Login page when the URL contained a port

Fixes #4261

CHANGELOG-v3.md

@@ -22,6 +22,7 @@
 - Fixed a bug where you could get some character encoding issues in some environments when using PHP 7.3.
 - Fixed a bug where Craft wasn’t attempting to set a unique URI on duplicated elements. ([#4253](https://github.com/craftcms/cms/issues/4253))
 - Fixed a bug where Table fields could copy cell values to other cells if a column had a handle in the format of “colX”. ([#4200](https://github.com/craftcms/cms/issues/4200))
+- Fixed an error that could occur on the Login page if a custom Login Page Logo was selected and the Control Panel URL contained a port number. ([#4261](https://github.com/craftcms/cms/issues/4261))
 
 ## 3.1.26 - 2019-05-08
 

src/templates/login.html

@@ -34,7 +34,7 @@
                     '<form id="login-form" method="post" accept-charset="UTF-8" {% if hasLogo -%}
             {%- set logo = craft.rebrand.logo -%}
             {%- set padding = logo.height + 30 -%}
-        class="has-logo" style="background-image: url(\'{{ logo.url }}\'); background-size: {{ logo.width }}px {{ logo.height }}px; padding-top: {{ padding }}px; margin-top: -{{ ((353+padding)/2)|round }}px"
+        class="has-logo" style="background-image: url({{ logo.url }}); background-size: {{ logo.width }}px {{ logo.height }}px; padding-top: {{ padding }}px; margin-top: -{{ ((353+padding)/2)|round }}px"
                 {%- endif %}>' +
             '{% if not hasLogo -%}<h1>{{ systemName }}</h1>{%- endif %}'+
             "{{ forms.textField({ id: 'loginName', name: 'username', placeholder: usernamePlaceholder, value: username, autocomplete: 'username', type: usernameType })|e('js') }}" +