Description of problem:
Observed that sorting based on "Available" quantity on "All available subscriptions" tab is not sorting correctly

Version-Release number of selected component (if applicable):
subscription-manager version
server type: Red Hat Subscription Management
subscription management server: 0.8.29-1
subscription-manager: 1.10.3-1.git.3.d610508.el7
python-rhsm: 1.10.3-1.git.0.6ac2883.el7


How reproducible:
4/4

Steps to Reproduce:
1.Register machine to candlepin server
2.Launch sub-man-gui
3.Move to "All available subscriptions"
4.Click on update ( with 'match my  system', 'have no overlap with existing subscriptions' selected)
5.sort based on the "Available" subscriptions 

Actual results:
Observed that the sorting is not working (PFA)

Expected results:
sorting based on the "Available" subscription should list the subscriptions based on the available subscriptions

Additional info:

observed that when less number of available subscriptions are present the sort is working as exepected, example list subscription for match installed products (say only 3 products are installed)