So the whole patch depends on the fact that all the imported snippets got *all* locales. So to revert this we need to delete all first. 

If we're going to use this code on snippets that were modified after the initial import maybe we need to take another approach:

In this case we can check if the list of current locales is not all locales, then we can augment the list with CMR as you suggest. If it's all locales, that's _probably_ from the import so we delete all current locales and we calculate from CMR. 

This doesn't cover the case where we did actually select all locales from the list.