better support for using checksummed file timestamps as a higher resolution file timestamp
better support for using checksummed file timestamps as a higher resolution file timestamp

bunbun/ruffus,aeron15/ruffus,magosil86/ruffus,pombreda/ruffus,pombreda/ruffus,kmonsoor/ruffus,d4g33z/ruffus,jigneshvasoya/ruffus