builder/virtualbox/common/step_shutdown_test.go: compare durations  instead of floats & ouput duration
builder/virtualbox/common/step_shutdown_test.go: compare durations  instead of floats & ouput duration

mkuzmin/packer,bryson/packer,youhong316/packer,mitchellh/packer,dave2/packer,dave2/packer,mitchellh/packer,paulmey/packer,hashicorp/packer,youhong316/packer,grubernaut/packer,mkuzmin/packer,tb3088/packer,tb3088/packer,ricardclau/packer,paulmey/packer,hashicorp/packer,bryson/packer,grubernaut/packer,hashicorp/packer,ricardclau/packer,ricardclau/packer,grubernaut/packer,timsutton/packer,grubernaut/packer,pecigonzalo/packer,tas50/packer,tas50/packer,timsutton/packer,bryson/packer,rnaveiras/packer,mkuzmin/packer,rnaveiras/packer,tb3088/packer,dave2/packer,tas50/packer,pecigonzalo/packer,mkuzmin/packer,dave2/packer,pecigonzalo/packer,rnaveiras/packer,paulmey/packer,rnaveiras/packer,hashicorp/packer,dave2/packer,tb3088/packer,tas50/packer,mitchellh/packer,pecigonzalo/packer,youhong316/packer,mitchellh/packer,timsutton/packer,mkuzmin/packer,ricardclau/packer,dave2/packer,timsutton/packer,tb3088/packer,paulmey/packer,timsutton/packer,youhong316/packer,mkuzmin/packer,mitchellh/packer,rnaveiras/packer,grubernaut/packer,tb3088/packer,bryson/packer,youhong316/packer,timsutton/packer,rnaveiras/packer,ricardclau/packer,paulmey/packer,tas50/packer,bryson/packer,youhong316/packer,grubernaut/packer,paulmey/packer,bryson/packer,tas50/packer,ricardclau/packer