I would think this is at least partly intended, since years 201, 500 and 1 can be valid dates (although long ago). But automatically converting 0001 to 2001, but not 0201 to 2201 seems inconsistent.
*Edit: Experimentally found: currently
- Every year between '00' and '33' is converted to '20xx'.
- Everything between '34' and '99' is converted to '19xx'.
- Everything with leading zeroes is converted according to the above, but subject to the below.
- Entering a single digit is always incorrect.
- Entering with 5 digits is always incorrect.
- Everything above 100 is a year by itself.