Bug 10070: fix saving searches with non-ASCII characters to anonymous search history

To test
1/ logout
2/ search "bar" (added to the history)
3/ search "féé" => history is empty

Apply patch
1/ logout
2/ search "bar" (added to the history)
3/ search "féé" => added to the history

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>