Description of problem:

As a result of many individual parts of automation and inheritance related to server provisioning, we might end up with duplicate activation-keys. 

This apperently results in an SQL-error on the server trying to register:

[root@hostname ~]# subscription-manager register --name="hostname.example.com" --org='Example' --activationkey='act-auto-attach-vdc,act-Verification-cv-soe-7Server,act-Verification-cv-soe-7Server'
HTTP error (500 - Internal Server Error): PG::UniqueViolation: ERROR:  duplicate key value violates unique constraint "katello_subscription_facet_activation_keys_sa_ak_id"
DETAIL:  Key (subscription_facet_id, activation_key_id)=(3530, 24) already exists.
: INSERT INTO "katello_subscription_facet_activation_keys" ("subscription_facet_id", "activation_key_id") VALUES ($1, $2) RETURNING "id"


In order to avoid encountering the error described above, the customer would like to have an enhanced version of subscription-manager, which is capable of identifying multiple activation key values specified using the --activationkey command-line option, and automatically supressing the duplicate values (if any).


The customer would test to confirm that the requirement is successfully implemented by executing a 'subscription-manager register' command that has duplicate activation key values specified using the --activationkey command-line option. For example:
~~~
[root@hostname ~]# subscription-manager register --name="hostname.example.com" --org='Example' --activationkey='act-auto-attach-vdc,act-Verification-cv-soe-7Server,act-Verification-cv-soe-7Server'
~~~


How reproducible:


Steps to Reproduce:
1. Perform a complete a basic kickstart-based installation using satellite
2. Try to register the newly installed host using subscription-manager with a valid activation-key mentioned 2 times (or more).


Actual results:

The following error message is received, and the host registration fails:
~~~
HTTP error (500 - Internal Server Error): PG::UniqueViolation: ERROR:  duplicate key value violates unique constraint "katello_subscription_facet_activation_keys_sa_ak_id"
DETAIL:  Key (subscription_facet_id, activation_key_id)=(3530, 24) already exists.
: INSERT INTO "katello_subscription_facet_activation_keys" ("subscription_facet_id", "activation_key_id") VALUES ($1, $2) RETURNING "id"
~~~


Expected results:

subscription-manager would be able to intelligently identify that there is a duplicate activation key specified, and suppress it, resulting in a successful system registration.