critical log instead of crashing in case of deleted .COPYING file

Script/CopyThread.py

@@ -359,8 +359,14 @@ class CopyThread(threading.Thread):
                     self.logger.critical('No connection to Metadata database: database will not be updated for file %s', DataFile)
 
                 ##### Copy successfull: rename .data.COPYING in .data.COPIED #####
-                os.rename(DataFile + Constants.copying_ext,
-                          DataFile + Constants.copied_ext)
+                try:
+                    os.rename(DataFile + Constants.copying_ext,
+                              DataFile + Constants.copied_ext)
+                except OSError as exc:
+                    if exc.errno == errno.ENOENT:
+                        self.logger.critical('error renaming %s: not present (deleted by external cause)', DataFile + Constants.copying_ext)
+                    else:
+                        raise exc
 
                 if self.conf.DdmMonitoringEnabled:
                     self.publishInDdmMonitoring(