Replaces sub execution with legacy implementation
Replaces sub execution with legacy implementation

No functional change from legacy implementation

[#108283324](https://www.pivotaltracker.com/story/show/108283324)

Signed-off-by: Jonathan Barnes <bc7add126c2dbb8382bf1c28ac262b9363a32706@pivotal.io>

pivotal-cf-experimental/bosh-tools,pivotal-cf-experimental/bosh-tools,pivotal-cf-experimental/bosh-tools