Allows the ssh-key test to pass when ran in parallel with different branches.
```
$ make testacc TEST=./builtin/providers/packet TESTARGS='-run=TestAccPacketSSHKey_Basic'
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2017/03/14 11:10:28 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/packet -v -run=TestAccPacketSSHKey_Basic -timeout 120m
=== RUN TestAccPacketSSHKey_Basic
PASS
ok github.com/hashicorp/terraform/builtin/providers/packet 3.503s
```