allowed value list error

Taking the example allowed values list above, produces a $options array of:

Array
(
    [1] => 1
    [2] => 1
    [3] => ½
    [4] => +
    [5] => -
)

notice that for the first pair, the key is used for the label instead of the requested "0", it should be:

Array
(
    [1] => 0
    [2] => 1
    [3] => ½
    [4] => +
    [5] => -
)

When the allowed values list is parsed, the "0" value is being ignored because a (bool) test of "0" is false

$allowed_values[$field['field_name']][$key] = $value ? $value : $key;

The attached patch adds a isset() and a test for a empty string (in-case a allowed values line reads something like "2|" instead of "2|1")

Committed to D5 and D6 branches. Thanks !