toolkit: profiles and assumerole credentials issues

Reported by @ChintanRaval on Gitter:

The following setup fails to default to the right region:

~/.aws/credentials

[my-auth-account]
aws_access_key_id = xxxx
aws_secret_access_key = xxxx

~/.aws/config

[default]
output = json
region = us-east-1

[profile my-auth-account]
source_profile = default

[profile my-dev-account]
source_profile = my-auth-account
role_arn = arn:aws:iam::123456789012:role/MyDesiredRole
mfa_serial = arn:aws:iam::112233445566:mfa/myusername

[rix0rrr]

Okay so we’re NOT inconsistent with the CLI, it’s just that the CLI S3 API does not require a region and therefore does not complain.

Then I don’t see any further work here. I’m going to close this out if that’s okay with you. Feel free to reopen if you encounter further issues.

[rix0rrr]

Scenario tested:

~/.aws/config

[default]
output = json
region = eu-west-1

[profile Assumert]
region = us-east-1
# source_profile = default does not work either

[profile Assumable]
role_arn = arn:aws:iam::112233445566:role/Assumable
source_profile = Assumert

~/.aws/credentials

[Assumert]
aws_access_key_id = XXXXXXXXX
aws_secret_access_key = XXXXXXXXXXXXX

Following result:

$  aws --profile Assumable ec2 describe-availability-zones
You must specify a region. You can also configure your region by running "aws configure".