Page tree broken after search is cleared

[timobrembeck]

Describe the Bug

When the search form in the page tree is cleared, all pages are expanded by default, but the collapsing/expanding does not work as expected.

Maybe the source of the bug is the same as #1179 and it's not a browser caching problem after all? If so, maybe fixing this also fixes #1245 when we enable the browser cache again after the back-button.

Steps to Reproduce

1. Go to the page tree
2. Enter something into the seach bar and submit
3. Clear the search via the "x"
4. See broken page tree

Expected Behavior

The page tree should be fully collapsed and expanding should work normal

Actual Behavior

Everything is expanded and the tree becomes weird on toggling subpages

Additional Information

E.g. the following subtree:

Toggling the subpages only hides the middle level and the leaf pages are still visible