Year display header always shows current year after using pager

When you open a Year display and use the pager to display a prev/post year, the header displays always the current year.
That is a normal behavior of strtotime() according a note (3rd exactly) that you can find on the php manual :

The "Year (and just the year)" format only works if a time string has already been found -- otherwise this format is recognised as HH MM.

I join a patch that resolves that issue, hope this helps.