When upgrading from 3.0.3+ Build 201607 to 20160422 and non utf8-locale (like fi_FI or sv_SE) is used, the Quiz edit view becomes nonfunctional, because of Javascript error on line 84 of theme/yui_combo.php.

Debugger error message:
TypeError: t is undefined
M.form.dateselector.initPanel()
yui_combo.php:84
M.form.dateselector.init_date_selectors()
yui_combo.php:84
<anonymous>
modedit.php:1148
e._notify()
yui_combo.php:9
e.use/<()
yui_combo.php:9
e._notify()
yui_combo.php:9
e._use/T()
yui_combo.php:9
e.Loader.prototype._finish()
yui_combo.php:16
e.Loader.prototype._onSuccess()
yui_combo.php:16
e.Loader.prototype._insert/p()
yui_combo.php:17
e.Loader.prototype._insert()
yui_combo.php:17
e.Loader.prototype._insert/p()
yui_combo.php:17
e.Loader.prototype._insert/<.onSuccess()
yui_combo.php:17
s.prototype._finish()
yui_combo.php:12
s.prototype._next()
yui_combo.php:12
s.prototype._progress()
yui_combo.php:13
h()
yui_combo.php:12
yui_combo.php:84:1491

Debugging using the non-minimized version (moodle-form-dateselector.js) of
lib/form/yui/build/moodle-form-dateselector/moodle-form-dateselector-min.js
reveals that error occurs because config is not defined on line 87:
firstdayofweek: parseInt(config.firstdayofweek, 10),

This error does not appear if locale is left blank or UTF-8-locale (like if_FI.utf-8) is used on the "Language settings" -page. fi_FI is given as an example locale in the Finnish version of the Language settings.

Nonfunctional means that it is not possible to change Timing, Grade etc. -settings. Also the editor is not visible on the Description -field.

To reproduce the problem:
1. Go to Site administration >> Language >> Language settings
2. set Sitewide locale: fi_FI
3. Open a Quiz
4. Select Edit settings
Alternatively you can create new Quiz