Redirect grep error output to /dev/null
As it's OK that some derivatives do not have sources.list and therefore have no sources.patches, it is not nessessary to keep grep errors about the missing sources.patches file in the census output.
As it's OK that some derivatives do not have sources.list and therefore have no sources.patches, it is not nessessary to keep grep errors about the missing sources.patches file in the census output.