Avoid constructing a FileRef when we don't use it
Avoid constructing a FileRef when we don't use it

andcor02/mbed-os,mbedmicro/mbed,kjbracey-arm/mbed,mbedmicro/mbed,andcor02/mbed-os,kjbracey-arm/mbed,andcor02/mbed-os,mbedmicro/mbed,andcor02/mbed-os,mbedmicro/mbed,andcor02/mbed-os,mbedmicro/mbed,kjbracey-arm/mbed,kjbracey-arm/mbed,andcor02/mbed-os