(unncessary) Slow query for dedupes

The queries that retrieve the records to dedupe are extremely slow due to poor construction.

The use of the OR here makes it an unindexed query

{{SELECT t1.contact_id id1, t2.contact_id id2, 50 weight
-> FROM civicrm_email t1
-> JOIN civicrm_email t2 USING (email)
-> WHERE t1.contact_id < t2.contact_id
-> AND t1.email IS NOT NULL
-> AND t1.email <> ''
-> AND (t1.contact_id IN (4279,68563,88888)
-> OR t2.contact_id IN (4279,68563,88888))
-> GROUP BY id1, id2 }}

Although the query does not return any results it is extremely slow on a large dataset. I only left it for 15 minutes or so before killing it but by comparison the equivalent query with a unit took 0.01 seconds

SELECT t1.contact_id id1, t2.contact_id id2, 50 weight
-> FROM civicrm_email t1
-> JOIN civicrm_email t2 USING (email)
-> WHERE t1.contact_id < t2.contact_id
-> AND t1.email = '%'
-> AND (t1.contact_id IN (4279,68563,88888) )
-> #OR t2.contact_id IN (4279,68563,88888))
-> GROUP BY id1, id2
->
-> UNION
->
-> SELECT t1.contact_id id1, t2.contact_id id2, 50 weight
-> FROM civicrm_email t1
-> JOIN civicrm_email t2 USING (email)
-> WHERE t1.contact_id < t2.contact_id
-> AND t1.email = '%'
-> AND (t2.contact_id IN (4279,68563,88888) )
-> #OR t2.contact_id IN (4279,68563,88888))
-> GROUP BY id1, id2
-> ;