Modified CVEs need reset of database
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We currently assume that, once a CVE is assigned, modifications to the CVE
include additional CPE matches, but the original ones remain. However, this is
not always the case. We should seek a way to clear the CVE<>CPE mappings.

Not easy as, by design, we load in information one line at a time. Perhaps
include a special line in the CSV that sais "please clear and continue"?
