terraform debug output after iam module configuration

gistfile1.txt

* aws_lambda_function.heartbeat: diffs didn't match during apply. This is a bug with Terraform and should be reported as a GitHub Issue.

Please include the following information in your report:

    Terraform Version: 0.7.3
    Resource ID: aws_lambda_function.heartbeat
    Mismatch reason: attribute mismatch: role
    Diff One (usually from plan): *terraform.InstanceDiff{mu:sync.Mutex{state:0, sema:0x0}, Attributes:map[string]*terraform.ResourceAttrDiff{"role":*terraform.ResourceAttrDiff{Old:"arn:aws:iam::413359656938:role/exp_cf_lambda_dynamodb_datafull", New:"${module.iam.lambda_function_role_id}", NewComputed:false, NewRemoved:false, NewExtra:interface {}(nil), RequiresNew:false, Sensitive:false, Type:0x0}}, Destroy:false, DestroyTainted:false}
    Diff Two (usually from apply): *terraform.InstanceDiff{mu:sync.Mutex{state:0, sema:0x0}, Attributes:map[string]*terraform.ResourceAttrDiff(nil), Destroy:false, DestroyTainted:false}

Also include as much context as you can about your config, state, and the steps you performed to trigger this error.