Incorrect obsolete ref

[frivoal]

As reported by @tabatkins, extracted from https://github.com/tobie/specref/issues/347#issuecomment-293434102

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the following refs are marked as being obsolete, but the thing they claim should obsolete them doesn't exist in the db:

nic15392
ien115
ien119
nic15390
ien123
ien133
nic18640
nic15389
nic16238
nic16239

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@tobie had replied:

Wow. That is weird and should have been caught by the the test suite. Need to dig into this to find what the problem is.