Fix conf.py for external versions (#7845)

Only evaluate on external versions

Author: stsewd

readthedocs/doc_builder/backends/sphinx.py

@@ -156,6 +156,10 @@ def get_config_params(self):
             protocol = 'http' if settings.DEBUG else 'https'
             build_url = f'{protocol}://{settings.PRODUCTION_DOMAIN}{build_url}'
 
+        vcs_url = None
+        if self.version.is_external:
+            vcs_url = self.version.vcs_url
+
         data = {
             'html_theme': 'sphinx_rtd_theme',
             'html_theme_import': 'sphinx_rtd_theme',
@@ -170,6 +174,7 @@ def get_config_params(self):
             'downloads': downloads,
             'subproject_urls': subproject_urls,
             'build_url': build_url,
+            'vcs_url': vcs_url,
 
             # GitHub
             'github_user': github_user,

readthedocs/doc_builder/templates/doc_builder/conf.py.tmpl

@@ -154,7 +154,7 @@ else:
 # Add External version warning banner to the external version documentation
 if '{{ version.type }}' == 'external':
     extensions.insert(1, "readthedocs_ext.external_version_warning")
-    readthedocs_vcs_url = '{{ version.vcs_url }}'
+    readthedocs_vcs_url = '{{ vcs_url }}'
     readthedocs_build_url = '{{ build_url }}'
 
 project_language = '{{ project.language }}'