Possibly bug: creating case from imported email.

[dimyy]

Situation:

Receive Email1 -> Create case1 -> Reply Email1_r1
Receive Email2 -> Creatie case2 -> Reply Email2_r1

Merge case1 + case2 (case1 marked deleted)

Receive Email1_r1_r2 -> binded with deleted case1, not actual case2