[FIX] snippets: properly unwrap during xml upgrade

We wrap the content to upgrade into a `<wrap>` element before upgrading
it. After the upgrade, we unwrap the content using `re.sub`... but this
did not consider the case where there is no content in the wrapper
anymore. Indeed, in that case, the XML formatter sets the content to
"<wrap/>" and not "<wrap></wrap>".

Related to community odoo/odoo#172755
Related to enterprise odoo/enterprise#66488
Related to upgrade odoo/upgrade#6254
Related to task-4008369

closes #113

Related: odoo/odoo#172755
Related: odoo/enterprise#66488
Related: odoo/upgrade#6254
Signed-off-by: Alvaro Fuentes Suarez (afu) <[email protected]>

Author: qsm-odoo

src/util/snippets.py

@@ -205,7 +205,7 @@ def __call__(self, content):
         )
         has_changed = self.has_changed(els)
         new_content = (
-            re.sub(r"(^<wrap>|</wrap>$)", "", etree.tostring(els, encoding="unicode").strip())
+            re.sub(r"(^<wrap>|</wrap>$|^<wrap/>$)", "", etree.tostring(els, encoding="unicode").strip())
             if has_changed
             else content
         )