GCS: Fix bug where around retry on GCS
GCS: Fix bug where around retry on GCS

We were recomputing the MD5, but we would need to rewind the stream first.

justinsb/kops,robinpercy/kops,kubernetes/kops,robinpercy/kops,robinpercy/kops,robinpercy/kops,justinsb/kops,kubernetes/kops,justinsb/kops,kubernetes/kops