I've seen this error, but only in one case. It looks like it's calling write before setup.
I tried adding @gs_bucket = initialize_bucket unless @gs_bucket before the write but it didn't help. I don't get the error, but it doesn't write the file, timeout or error in another way.
I am writing to a bucket in the US and only experience this issue from europe-west1. It works fine from my instances in us-central1 and AWS us-east-1.
All the instances are setup with puppet so I doubt there is any environmental differences.
Any ideas?