Cannot set a password containing umlauts (äüö)

Go to myplonesite.org/@@change-password (or "My Setting" => "Password" tab)

Then try to change your old password to one that contains Umlauts like Ä, ä, Ö, ö, Ü or ü.

Then you get the following traceback:

Traceback (innermost last):
  Module ZPublisher.Publish, line 138, in publish
  Module ZPublisher.mapply, line 77, in mapply
  Module ZPublisher.Publish, line 48, in call_object
  Module zope.formlib.form, line 795, in __call__
  Module five.formlib.formbase, line 50, in update
  Module zope.formlib.form, line 776, in update
  Module zope.formlib.form, line 620, in success
  Module plone.app.users.browser.personalpreferences, line 471, in action_reset_passwd
  Module <string>, line 4, in setPassword
  Module plone.protect.utils, line 46, in _curried
  Module <string>, line 4, in setPassword
  Module AccessControl.requestmethod, line 70, in _curried
  Module Products.PlonePAS.tools.membership, line 572, in setPassword
  Module Products.PlonePAS.pas, line 100, in _doChangeUser
  Module Products.PlonePAS.pas, line 365, in userSetPassword
  Module Products.PloneLDAP.mixins.usermgmt, line 22, in doChangeUser
  Module Products.LDAPUserFolder.LDAPUserFolder, line 1688, in manage_editUserPassword
  Module Products.LDAPUserFolder.utils, line 87, in _createLDAPPassword
  Module AccessControl.AuthEncoding, line 220, in pw_encrypt
  Module AccessControl.AuthEncoding, line 117, in encrypt
UnicodeEncodeError: 'ascii' codec can't encode character u'\xc4' in position 3: ordinal not in range(128)

Might be related to https://bugs.launchpad.net/ldapuserfolder/+bug/898921