fix html escape error

TNL-3822

cms/templates/container.html

@@ -11,6 +11,7 @@ else:
 from contentstore.views.helpers import xblock_studio_url, xblock_type_display_name
 from django.utils.translation import ugettext as _
 from openedx.core.lib.js_utils import escape_json_dumps
+from markupsafe import Markup as HTML, escape as HTML_ESCAPE
 %>
 <%block name="title">${xblock.display_name_with_default} ${xblock_type_display_name(xblock) | h}</%block>
 <%block name="bodyclass">is-signedin course container view-container</%block>
@@ -110,10 +111,10 @@ from openedx.core.lib.js_utils import escape_json_dumps
                 % if xblock.category == 'split_test':
                     <div class="bit">
                         <h3 class="title-3">${_("Adding components")}</h3>
-                        <p>${_("Select a component type under {em_start}Add New Component{em_end}. Then select a template.").format(em_start='<strong>', em_end="</strong>") | h}</p>
+                        <p>${_(HTML_ESCAPE("Select a component type under {em_start}Add New Component{em_end}. Then select a template.")).format(em_start=HTML('<strong>'), em_end=HTML("</strong>"))}</p>
                         <p>${_("The new component is added at the bottom of the page or group. You can then edit and move the component.")}</p>
                         <h3 class="title-3">${_("Editing components")}</h3>
-                        <p>${_("Click the {em_start}Edit{em_end} icon in a component to edit its content.").format(em_start='<strong>', em_end="</strong>") | h}</p>
+                        <p>${_(HTML_ESCAPE("Click the {em_start}Edit{em_end} icon in a component to edit its content.")).format(em_start=HTML('<strong>'), em_end=HTML("</strong>"))}</p>
                         <h3 class="title-3">${_("Reorganizing components")}</h3>
                         <p>${_("Drag components to new locations within this component.")}</p>
                         <p>${_("For content experiments, you can drag components to other groups.")}</p>