[FIX] ir_cron: use the same search criteria as when listing job to excecyte...

[FIX] ir_cron: use the same search criteria as when listing job to excecyte when acquiring the ock on the job before its execution to prevent running already executed job

Backport of fix made in trunk

openerp/addons/base/ir/ir_cron.py

@@ -216,12 +216,21 @@ class ir_cron(osv.osv):
             lock_cr = db.cursor()
             try:
                 # Try to grab an exclusive lock on the job row from within the task transaction
+                # Restrict to the same conditions as for the search since the job may have already
+                # been run by an other thread when cron is running in multi thread
                 lock_cr.execute("""SELECT *
                                    FROM ir_cron
-                                   WHERE id=%s
+                                   WHERE numbercall != 0
+                                      AND active
+                                      AND nextcall <= (now() at time zone 'UTC')
+                                      AND id=%s
                                    FOR UPDATE NOWAIT""",
                                (job['id'],), log_exceptions=False)
 
+                locked_job = lock_cr.fetchone()
+                if not locked_job:
+                    _logger.debug("Job `%s` already executed by another process/thread. skipping it", job['name'])
+                    continue
                 # Got the lock on the job row, run its code
                 _logger.debug('Starting job `%s`.', job['name'])
                 job_cr = db.cursor()