Description of problem:
The the code of aws scale group call the python2-botocore to interact with AWS, but the botocore rpm in aos repo (which version is python2-botocore-1.4.57-5.el7.noarch.rpm) doesn't satisfy this requirement.

The bug has been reported at: https://bugzilla.redhat.com/show_bug.cgi?id=1605160,

The workaround of this problem is done by following:
    pip install --upgrade botocore==1.7.0

Version-Release number of the following components:
openshift-ansible-3.11.0-0.34.0-16-gbef0926
python2-botocore-1.4.57-5.el7.noarch.rpm 

How reproducible:
100%

Steps to Reproduce:
1. ansible-playbook -i inventory.yml -e @provisioning_vars.yml playbooks/aws/openshift-cluster/prerequisites.yml
2.
3.

Actual results:
Fail to create aws scale group
fatal: [localhost]: FAILED! => {
    "changed": false,  
    "module_stderr": "Traceback (most recent call last):\n  File \"/tmp/ansible__Lhwy2/ansible_module_ec2_vpc_net.py\", line 477, in <module>\n    main()\n  File \"/tmp/ansible__Lhwy2/ansible_module_ec2_vpc_net.py\", line 383, in main\n    vpc_id = create_vpc(connection, module, cidr_block[0], tenancy)\n  File \"/tmp/ansible__Lhwy2/ansible_module_ec2_vpc_net.py\", line 293, in create_vpc\n    connection.get_waiter('vpc_exists').wait(VpcIds=[vpc_obj['Vpc']['VpcId']])\n  File \"/usr/lib/python2.7/site-packages/botocore/client.py\", line 632, in get_waiter\n    raise ValueError(\"Waiter does not exist: %s\" % waiter_name)\nValueError: Waiter does not exist: vpc_exists\n",                                                      
    "module_stdout": "",  
    "msg": "MODULE FAILURE",  
    "rc": 1
}

Expected results:
Create aws scale group success

Additional info:
Please attach logs from ansible-playbook with the -vvv flag