Merge pull request #15856 from edx/nedbat/fix-field-i18n

XBlock fields with formatted-in values can now translate properly

cms/djangoapps/models/settings/course_metadata.py

@@ -140,10 +140,16 @@ class CourseMetadata(object):
         for field in descriptor.fields.values():
             if field.scope != Scope.settings:
                 continue
+
+            field_help = _(field.help)                  # pylint: disable=translation-of-non-string
+            help_args = field.runtime_options.get('help_format_args')
+            if help_args is not None:
+                field_help = field_help.format(**help_args)
+
             result[field.name] = {
                 'value': field.read_json(descriptor),
                 'display_name': _(field.display_name),    # pylint: disable=translation-of-non-string
-                'help': _(field.help),                    # pylint: disable=translation-of-non-string
+                'help': field_help,
                 'deprecated': field.runtime_options.get('deprecated', False)
             }
         return result

common/lib/xmodule/xmodule/course_module.py

@@ -732,7 +732,8 @@ class CourseFields(object):
             'For example, to specify that teams should have a maximum of 5 participants and provide a list of '
             '2 topics, enter the configuration in this format: {example_format}. '
             'In "id" values, the only supported special characters are underscore, hyphen, and period.'
-        ).format(
+        ),
+        help_format_args=dict(
             # Put the sample JSON into a format variable so that translators
             # don't muck with it.
             example_format=(

common/lib/xmodule/xmodule/modulestore/inheritance.py

@@ -178,7 +178,8 @@ class InheritanceMixin(XBlockMixin):
             "Identify a video, 5-10 seconds in length, to play before course videos. Enter the video ID from "
             "the Video Uploads page and one or more transcript files in the following format: {format}. "
             "For example, an entry for a video with two transcripts looks like this: {example}"
-        ).format(
+        ),
+        help_format_args=dict(
             format='{"video_id": "ID", "transcripts": {"language": "/static/filename.srt"}}',
             example=(
                 '{'