Popup date picker gives invalid value with abbreviated day names including non-English (Hungarian) letters.

In Hungarian the day names from Monday to Sunday are Hétfő (mon), Kedd (tue), Szerda (wed), Csütörtök (thurs), Péntek(fri), Szombat(sat) and Vasárnap (sun).

I used the jQuery popup picker as so it would also show the name of the day. Sometime, after submitting it returned an error indicating that the date format was invalid. The problem only occures on Mondays, Thursdays, Fridays and Sundays (the days that have non-english characters), and interestingly only when I set the imput form as so it shows an abbreviated day name (hét. ked. sze. csü. pén. szo. vas.). It works well with tuesdays, wednesdays and saturdays, or if I turn the input form to a non-abbreviated day name.

I hope I didn't make it too confusing, maybe the screenshot clears something.