delete of vocabulary not always working

[marc-portier]

We have encountered a number of cases where delete of vocabulary does not seem to work.
When this happens - the status (is it still being deleted?) of the vocab becomes rather unclear.

In those cases we (up to now) have each time found out that deleting the associated "sources" to the vocabulary first does seem to work. After the vocab has no more sources associated, the delete on vocab level does seem to work.