Cannot expand/collapse navigation tree container while on Permissions tab

Steps to reproduce on nightly.nuxeo.com w/distribution 7.10 - 201510190329:

1. Create a workspace
2. Navigate to workspace Permissions tab
3. Select Collapse icon on Workspaces in Navigation Tree
4. Notice Navigation Tree Workspaces collapses as expected
5. Repeatedly select Expand icon on Workspaces in Navigation Tree

Error: Notice Workspaces Navigation Tree refuses to expand

Also note that the above steps performed with Step #2 navigating to workspace Content tab does not exhibit this erroneous behavior