Fix copy test failure in postgres HEAD
Fix copy test failure in postgres HEAD

Commit 4fe384bd858671d40d311ca68cc9b80f4c683a3e changed the way this
works on postgres side, which sometimes caused this test to fail.

beni55/pq,springning/pq,bugreplaydev/pq,bugreplaydev/pq,sammi/pq,StabbyCutyou/pq,amaniak/pq,calebthompson/pq,henrylee2cn/pq,dongzerun/pq,ScriptRock/pq,VividCortex/pq,lib/pq,everalbum/pq,jnewmano/pq,cbandy/go-pq,jnewmano/pq,erichnascimento/pq,stvp/pq,johto/pq,ympons/pq,ympons/pq