current employer not recached on org merge

to recreate:

• create Test1 Contact with current employer Org1
• create Test2 Contact with current employer Org 2
• merge Org 1 and Org 2
• reload Test1 and Test1

the current employer value which displays in the summary tab (a cached value stored in the organization_name column) remains the same. if you click the inline block to go to form view for the contact whose org should have changed, you'll see it's set correctly, and upon saving it's re-cached correctly.