Unable to connect to database when execute lampstack workload again

[Eric Xie]

Description
===========
The workload 'lampstack' was fail at the first time.
Then executed it again, got the 'unable to connect to database' error.

Steps to reproduce
==================
* Clone the latest source
git clone https://github.com/openstack/interop-workloads.git
* Create my cloud's vars file
* Execute ansible-playbook
ansible-playbook -e "action=apply env=inspur password=interop" site.yml

Expected result
===============
SUCCESS

Actual result
=============
Failure

Environment
===========
1. interop-workloads version
# git log
commit a25de91b6e77487060d3035b4202a48e0a5b2b2f
Merge: 3e4d4e8 2c89e57
Author: Jenkins <email address hidden>
Date: Wed Mar 22 14:55:01 2017 +0000

    Merge "Kubernetes workload"

2. Which workload did you use?
lampstack

Logs
===========
TASK [database : Update MySQL root password for all root accounts] *************
failed: [172.23.48.28] (item=127.0.0.1) => {"failed": true, "item": "127.0.0.1", "msg": "unable to connect to database, check login_user and login_password are correct or /root/.my.cnf has the credentials. Exception message: (1045, \"Access denied for user 'root'@'localhost' (using password: NO)\")"}
failed: [172.23.48.28] (item=localhost) => {"failed": true, "item": "localhost", "msg": "unable to connect to database, check login_user and login_password are correct or /root/.my.cnf has the credentials. Exception message: (1045, \"Access denied for user 'root'@'localhost' (using password: NO)\")"}
 to retry, use: --limit @/home/interop-workloads/workloads/ansible/shade/lampstack/site.retry