user_key is formed before attributes are modified by the extension config

[Luci2015]

Description
user_key is formed before attributes are modified by the extension config.
In case the email gets modified in this process, the user_key gets created with the initial email value extracted from directory

Steps to reproduce

• use an extension config where the email is modified to be equal to username, equal to something different than what's extracted from directory as 'mail' attribute
• run UST and observe that queueing will be seen for accts with user_key using initial email account and removing the ones that have the correct/expected user_key for same account.

Expected behavior
keys should be matching in this case and above situation be avoided

Environment

• UST version: all
• OS type and version: all