Fixed possible db error log spam when cluster=* in wfWaitForSlaves()

Change-Id: Idd385cddb0fa9f56bddc46d41ae584ca65bc45ed
(cherry picked from commit 5e5bf769fef92fbf2cbbe99b8c9de8f8474d31e0)
Merge "Fixed possible db error log spam when cluster=* in wfWaitForSlaves()" into wmf/1.25wmf6