What happended to the ability to expand parent groups in the Manage Groups page?
As you noted in the comments below, there is a JIRA discussion about this issue. The issue has been tracked down, and a patch submitted (which is now in Q&amp;A and slated for 4.7.8).

Per @jitendrapurohit on the Jira thread above:


  Submitted a PR - https://github.com/civicrm/civicrm-core/pull/8323
  
  1) First issue mentioned above was the regression of CRM-18184. Seems
  the patch attached on that was different from the PR submitted. This
  was later fixed in this PR
  https://github.com/civicrm/civicrm-core/pull/8020
  
  2) Second point was a regression of this commit. The updated params
  loses the key('parentsOnly') sent from $_GET.