Issue #1875020 by longwave, David_Rothstein, slip, alexpott, catch,...

Issue #1875020 by longwave, David_Rothstein, slip, alexpott, catch, smustgrave, jhodgdon: Cron queue gets processed every time cron is called, regardless of whether it's already being processed elsewhere

(cherry picked from commit d06dfb35)
(cherry picked from commit e910452a)