Import (update) date into custom date field ignores incoming date value

Attempting to import a record (using update) which contains a value to overwrite a custom date field does not result in the custom date field being set to the incoming value.

The following are the steps using in the 1.5 demo to reproduce the problem.

1) Setup:
1a) Create a new custom data set. Add one DATE type custom field ("Last Called") to the set. An image of the custom field defn is attached.
1b) Set the duplicate matching criteria to just "Internal Contact ID".
1c) Create or find a contact to use for the test. (I created "Mark Batten-Carew" for this.) Determine the Contact ID. (135 in my case.)
1c) Prepare an input CSV file with a single record, such as First Name, Last Name, Internal Contact ID, Last Called, and fill in the record with Mark, Batten-Carew, 135, 2006-08-23 (The input file I used is also attached.)

2) Do the import - the four steps of the import wizard are shown in the attached images.

3) Apparently the import is successful, but when you search for "Mark" and view the Batten-Carew record, Last Called is displayed as 0 00.

I also tried to go back and change the field defn so it would allow dates up to 1 year in the future (maybe 0 years in the future doesn't work) and re-ran the import, but the effect was the same.

In my tests on 1.4, I actually imported (using update) a number of fields in addition to the LAST CALLED date and all others were imported correctly (those record values were updated appropriately).

I would like to back-port the fix in 1.5 to my instance of 1.4, so it would be great if a detailed set of edits and files affected could be recorded.

Thanks.