Bug fix for ATLJETMET-600
Fixes ATLJETMET-600. Bug fix to check status of isSubtracted before setting it - its expected it may already be set, and so we don't need to set it if so (which will remove WARNING from log files).
Fixes ATLJETMET-600. Bug fix to check status of isSubtracted before setting it - its expected it may already be set, and so we don't need to set it if so (which will remove WARNING from log files).