Package command uploads entire directory when using SAM InlineCode

SAM recently released support for `InlineCode`, however, when the package command gets run it zips+uploads the entire current directory (even though it doesn't get used). I believe this is the issue https://github.com/aws/aws-cli/blob/d0fd4d2e2856e441156c0ba333eb119c7abd977e/awscli/customizations/cloudformation/artifact_exporter.py#L125.

Repro:

Create a SAM template with the following Resource:

```yaml
MyFunction:
Type: AWS::Serverless::Function
Properties:
InlineCode: |
exports.handler = async (event) => {
return event
}
Handler: index.handler
Runtime: nodejs8.10
```

Run `aws cloudformation package` command.

Result: You can see the entire current directory gets zipped and uploaded to S3.

Expected: It doesn't.