jinja2: Use function interface for render_markdown_path.

Apparently, the filters implementation was doing some sort of strange
caching, where you would need to restart the server in order to
refresh for changes to the markdown content.

We fix this by switching to just calling the render_markdown_path
function from Jinja2.

Fixes zulip#5974.

Author: timabbott

templates/tests/test_markdown.html

@@ -1,5 +1,5 @@
 header
 
-{{ markdown_test_file|render_markdown_path }}
+{{ render_markdown_path(markdown_test_file) }}
 
 footer

templates/zerver/for-open-source.html

@@ -27,7 +27,7 @@ <h1 class="center">{% trans %}The best choice for open source projects{% endtran
     <div class="main">
         <div class="padded-content">
             <div class="inner-content">
-                {{ 'zerver/for/open-source.md'|render_markdown_path }}
+                {{ render_markdown_path('zerver/for/open-source.md') }}
             </div>
         </div>
     </div>

templates/zerver/help/main.html

@@ -5,14 +5,14 @@
 {% block portico_content %}
 <div class="app help terms-page inline-block">
     <div class="sidebar">
-        {{ "zerver/help/sidebar.md"|render_markdown_path }}
+        {{ render_markdown_path("zerver/help/sidebar.md") }}
     </div>
     <svg height="32px" class="hamburger" style="enable-background:new 0 0 32 32;" version="1.1" viewBox="0 0 32 32" width="32px" xml:space="preserve" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
         <path d="M4,10h24c1.104,0,2-0.896,2-2s-0.896-2-2-2H4C2.896,6,2,6.896,2,8S2.896,10,4,10z M28,14H4c-1.104,0-2,0.896-2,2  s0.896,2,2,2h24c1.104,0,2-0.896,2-2S29.104,14,28,14z M28,22H4c-1.104,0-2,0.896-2,2s0.896,2,2,2h24c1.104,0,2-0.896,2-2  S29.104,22,28,22z"></path>
     </svg>
     <div class="markdown">
         <div class="content">
-            {{ article|render_markdown_path }}
+            {{ render_markdown_path(article) }}
             <div id="footer" class="documentation-footer">
                 <hr />
                 <p>

templates/zerver/privacy.html

@@ -8,7 +8,7 @@
     <div class="app-main terms-page-container">
 
         {% if privacy_policy %}
-            {{ privacy_policy|render_markdown_path }}
+            {{ render_markdown_path(privacy_policy) }}
         {% else %}
             {% trans %}
             This installation of Zulip does not have a configured privacy policy.

templates/zerver/terms.html

@@ -7,7 +7,7 @@
 <div class="app terms-page inline-block">
     <div class="app-main terms-page-container">
         {% if terms_of_service %}
-            {{ terms_of_service|render_markdown_path }}
+            {{ render_markdown_path(terms_of_service) }}
         {% else %}
             {% trans %}
             This installation of Zulip does not have a configured terms of service.

templates/zerver/why-zulip.html

@@ -25,7 +25,7 @@ <h1 class="center">{% trans %}Why Zulip?{% endtrans %}</h1>
     <div class="main">
         <div class="padded-content">
             <div class="inner-content">
-                {{ 'zerver/why-zulip.md'|render_markdown_path }}
+                {{ render_markdown_path('zerver/why-zulip.md') }}
             </div>
         </div>
     </div>

zproject/jinja2/__init__.py

@@ -20,6 +20,7 @@ def environment(**options):
     env.globals.update({
         'static': staticfiles_storage.url,
         'url': reverse,
+        'render_markdown_path': render_markdown_path,
         'minified_js': minified_js,
     })
 
@@ -28,6 +29,5 @@ def environment(**options):
     env.filters['slugify'] = slugify
     env.filters['pluralize'] = pluralize
     env.filters['display_list'] = display_list
-    env.filters['render_markdown_path'] = render_markdown_path
 
     return env