Remove "Merge prep" log line
Remove "Merge prep" log line

Summary: This doesn't really provide any useful information

Reviewed By: gabelevi

Differential Revision: D18310725

fbshipit-source-id: 2dcdbe9dd566b5e65d869dbfe7e62305efce67e7

nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow