Description of problem:
  In the content page, there is possible to compare two different versions of one content view. However, the result is always wrong, as it shows the same amount of packages/erratas in both columns. Moreover, if you add a repository into a CV, then the link "Show 25 More" doesn't work and if you click on it, then you receive a message "Couldn't find Katello::KTEnvironment without an ID".

Version-Release number of selected component (if applicable):
6.1.2

How reproducible + steps to Reproduce:
1) Create a content view, add repository and publish it. Next add another repository and publish new version. Promote the new version to another Lifecycle environment afterwards, 

2) Go to Content -> Content Search,

3) Click on search,

4) Add another lifecycle environment using the plus button in the top right corner of the table with compare results,

5) Select the content view versions and click on "Compare selected",

6) You should be able to see two columns comparing the versions.

7) To see the error message mentioned above click on the repository, scroll down and click on the "Show 25 More" link.

Actual results:
The comparison shows no difference between the versions 

Expected results:
There will be visible differences in the comparison

Additional info:
  Possible related BZ: 
    #1212450
    #1262371
    #1241500