vincentsels/mantisbt — comment on commit 35800836dd315e12e7d552ee0f64519b9f60c693
File: core/date_api.php line 323
By dregad:

is_blank() will return true if $p_date is null, so this should be
```
if( !$p_allow_null && ( is_blank ( $p_date ) || date_is_null( $p_date ) ) ) {
```