Redmine

We often have some consecutive tasks with duration of few hours. All tasks must be solved in one day, but next task can't be solved while previous task is not solved. I create and issue 1, set begin date for example 2014-06-19 and finish date 2014-06-19. Then I create issue 2 with the same begin and finish date - 2014-06-19. Then I mark issue 1 as preceding to issue 2. After that begin date of issue 2 became 2014-06-20. If I try to change date back to 2014-06-19? I'm getting an error "Begin date cannot be earlier than 2014-06-20 because of preceding issues". Looks like redmine does not imply tasks less than one day. I found row 162 in issue_relation.rb
(issue_from.due_date || issue_from.start_date) + 1 + delay
And changed it to
(issue_from.due_date || issue_from.start_date) + delay
Now I can put consecutive tasks in one day. Is it possible to fix this in future versions of redmine?