7.9 - In Doc Link Picker Dialog, folder selection moves to parent if enter key pressed instead of clicking on search icon

For a document link field in document editor for a document, you can open the link picker dialog for the field.
In the dialog, select a descendant folder and enter a word in the search input textbox. If you type enter key instead of clicking on the search icon, the folder selection is moved to the parent folder of the originally selected folder.

Reproduction steps in 7.9

1. Checkout http://svn.onehippo.org/repos/hippo/hippo-cms7/testsuite/branches/hippo-testsuite-1.06.xx and build/run it.
2. Open news document type and add a new doc link field : Caption: "Related Document" and Path: "related", for instance. Save and commit the change.
3. Edit /content/documents/demosite/news/2009/01/launch-cms-7
4. Open link picker dialog for "Related Document" field
5. Select demosite/news/2009/01 folder on the left pane
6. Type "cms" in the search input text field on the left pane and type Enter key.
7. The folder selection moves to demosite/news/2009, not staying in demosite/news/2009/01.
   (If you click on search icon instead of typing enter key in the previous step, it stays in the originally selected folder with good search result.)

NOTE: This problem doesn't happen in 10. (Confirmed with testsuite-TRUNK)