clean up gettext output folder before updating po files

Author: flpm

noxfile.py

@@ -269,6 +269,7 @@ def update_release_languages(session):
     if RELEASE_LANGUAGES:
         session.install("-e", ".")
         session.install("sphinx-intl")
+        _clean_translation_templates(session)
         session.log("Updating templates (.pot)")
         session.run(
             SPHINX_BUILD,
@@ -298,6 +299,7 @@ def update_language(session):
         if lang in LANGUAGES:
             session.install("-e", ".")
             session.install("sphinx-intl")
+            _clean_translation_templates(session)
             session.log("Updating templates (.pot)")
             session.run(
                 SPHINX_BUILD,