Steps to reproduce
1. create 2 clients on same tenant
2. create BP1/user1 in client A and BP2/user2 in client B - enter same email address
3. create 2 webstore in client A. try to login - not working
4. change in Client B user2 email, try to login >> working
Solution: each webstore with specific webcontext is dedicated to a specific client. Limit User login email iteration (looking for credentials when login) to client webcontext is belonging.
version 3.0 26 oct. 2015
There is a pending issue where could be modified patch to add client validation.