ERP5VCS: check we don't do empty commits

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@44504 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5VCS/Subversion.py

@@ -244,6 +244,7 @@ class Subversion(WorkingCopy):
     selected_set = set(added)
     selected_set.update(modified)
     selected_set.update(removed)
+    assert selected_set, "nothing to commit"
     self.revert('.', recurse=True, exclude_set=selected_set)
     revision = self._getClient().checkin('.', changelog, True)
     return context.REQUEST.RESPONSE.redirect('%s/view?%s' % (