Bug 1008931

Description of problem:
After subscribe zero instance-base subscription(instance-multiplier is 2) in the SAM web UI, it will subscribe it successfuly, But the attached quantity is 1

Version-Release number of selected component (if applicable):
subscription-manager-1.8.22-1.el5
python-rhsm-1.8.17-1.el5
virt-who-0.7-9.el5
katello-headpin-1.4.3-13.el6sam_splice.noarch
candlepin-0.8.26-1.el6sam.noarch

How reproducible:
Always

Steps to Reproduce:
ENV:SAM host:10.66.13.97, username/password:admin/admin
Prepare the instance-base subscription in the SAM as the following:
	Name: Red Hat Enterprise Linux Server, Premium
	Number: 
	SKU: RH00003
	Contract: 10023540
	Account: 5226325
	Service Level: Premium
	Service Type: L1-L3
	Quantity: 20
	Quantity Used: 2
	Socket Limit: 2
	RAM Limit: 
	Core Limit: 
	Virt Only: False
	Subscription: 
	Stacking ID: RH00003
	Warning Period: 0
	Provides Management: False

1. Register host to SAM server
#subscription-manager register --username=admin --password=admin
2. Open the SAM web UI with url:https://SAMIP/sam
3. Click on System-->All in the menu, Then click the host's hostname on the left list, it will see the host's information on the right side.
4. Click "Subscription" tab, check on the subscription of"Red Hat Linux Server, Premium"(instance-base subscription , and the instance-multiplier is 2) , modify the quantity to zero, Then click on "Attach" button
5. Check the part of "System Current Subscription(s)"

Actual results:
Subscription successfully, it remind "Insufficient Subscriptions are Attached". And the attached quantity is 1, please see the screenshot in the attachment.

Expected results:
Subscribe the subscription successfully, the attached quantity should be 2. As Physical systems can only consume in increments of the instance multiplier

Additional info:
If subscribe the non instance-base subscription , After subscribe the zero subscription in the SAM web UI , it also subscribe successfully ,and the quantity is 1, it means After attach the quantity of zero subscription in the SAM web UI, It should consume default quanity subscription.