Calendar misalignment with CJK locales

Khal doesn't display the calendar correctly when using LC_TIME values that require CJK fonts.
I've tested this with Chinese, Japanese and Korean locales (see below). These locales use full-width characters for weekdays and months, and full-width characters have a width of 2.

I think the underlying issue is in the Python standard library (bugs related to the calendar.LocaleTextCalendar class and about finding character width) but I found this when I was trying out khal so thought I'd raise it here.

$ LC_TIME=zh_CN.UTF-8 python -m khal
    一  二  三  四  五  六  日      No events
1月   1  2  3  4  5  6  7
 ...

$ LC_TIME=ko_KR.UTF-8 python -m khal
    월  화  수  목  금  토  일      No events
 1월  1  2  3  4  5  6  7 
 ...

$ LC_TIME=ja_JP.UTF-8 python -m khal
    月  火  水  木  金  土  日      No events
 1月  1  2  3  4  5  6  7

Reproduce the issue with the python -m khal entry point and the zh_CN, ko_KR, and ja_JP LC_TIME examples. Trace the calendar rendering and width handling, including the referenced Python calendar.LocaleTextCalendar behavior and character-width issue. Done means weekday and month labels align correctly for these CJK locales.