Partial XAR export still includes some non-selected pages

STEPS TO REPRODUCE

1. Go to Sandbox.WebHome and modify its content
2. Go to Administer Wiki > Content > Export
3. Click 'none' to remove all selection from the default filter
4. Click on 'Sandbox'
5. Click 'Export'

EXPECTED RESULTS

Only the pages related to Sandbox space and 'package.xml' page should be exported:

Sandbox/WebHome.xml     
Sandbox/WebHome.lv.xml
Sandbox/WebHome.it.xml
Sandbox/WebHome.zh_TW.xml
Sandbox/WebHome.de.xml
Sandbox/WebHome.fr.xml
Sandbox/WebHome.es.xml
Sandbox/WebHome.ca.xml
Sandbox/WebHome.da.xml
Sandbox/WebHome.uk.xml
Sandbox/WebHome.zh.xml
Sandbox/WebHome.ru.xml
Sandbox/WebHome.pt_BR.xml
package.xml

ACTUAL RESULTS

There are exported also the following pages:

XWiki/Admin.xml
XWiki/SearchConfig.xml
XWiki/Notifications/NotificationEmailHourlySender.xml

I've noticed that after selecting 'none' (Step 3) the XWiki space appears to be non-selected, but after click on tree node corresponding to XWiki space, the pages 'Admin.xml' and 'SearchConfig.xml' are still selected (valid also for 'NotificationEmailHourlySender.xml' if expanding the Notifications tree node).