Fix authconfig resolution when credStore is used combined with login()

[shin-]

Fixes #1861

cc @dnovvak can you verify that this solves your issue? Thanks!

[dnovvak]

Fix verified successfully. Thank you.

[DEBUG]: Using credentials store "wincred"
[DEBUG]: Looking for auth entry for 'XXX.amazonaws.com'
[DEBUG]: No entry found
[DEBUG]: No entry in credstore - fetching from auth dict
[DEBUG]: Looking for auth entry for 'XXX.amazonaws.com'
[DEBUG]: No entry found
[DEBUG]: http://localhost:None "POST /v1.36/auth HTTP/1.1" 200 48
[DEBUG]: {u'IdentityToken': u'', u'Status': u'Login Succeeded'}
[DEBUG]: Looking for auth config
[DEBUG]: Using credentials store "wincred"
[DEBUG]: Looking for auth entry for 'XXX.amazonaws.com'
[DEBUG]: No entry found
[DEBUG]: No entry in credstore - fetching from auth dict
[DEBUG]: Looking for auth entry for 'XXX.amazonaws.com'
[DEBUG]: Found 'XXX.amazonaws.com'
[DEBUG]: Found auth config
[DEBUG]: http://localhost:None "POST /v1.36/services/create HTTP/1.1" 201 35
[DEBUG]: http://localhost:None "GET /v1.36/services/sd2r0u0zynlvr30qb7qna68ac HTTP/1.1" 200 None