Fatal error when user accidentally uses duplicate transaction # while recording a contrib.

I have reproduced this in the public sandbox at: http://drupal.demo.civicrm.org/

Steps to reproduce:
1) Create a contribution using the transaction ID 12399 ( or any other number you make a note of)

2) Create another contribution using the same transaction ID as step 1. Upon clicking "Save" you will see the error message "Sorry but we are not able to provide this at the moment."

The stack trace is below:

#0 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Error.php(315): CRM_Core_Error::backtrace()
#1 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/DAO.php(744): CRM_Core_Error::fatal()
#2 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Contribute/Form/Contribution.php(1258): CRM_Core_DAO::getFieldValue("CRM_Pledge_DAO_PledgePayment", NULL, "id", "contribution_id")
#3 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Form.php(261): CRM_Contribute_Form_Contribution->postProcess()
#4 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/QuickForm/Action/Upload.php(151): CRM_Core_Form->mainProcess()
#5 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/QuickForm/Action/Upload.php(128): CRM_Core_QuickForm_Action_Upload->realPerform(Object(CRM_Contribute_Form_Contribution), "upload")
#6 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/packages/HTML/QuickForm/Controller.php(203): CRM_Core_QuickForm_Action_Upload->perform(Object(CRM_Contribute_Form_Contribution), "upload")
#7 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/packages/HTML/QuickForm/Page.php(103): HTML_QuickForm_Controller->handle(Object(CRM_Contribute_Form_Contribution), "upload")
#8 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Controller.php(345): HTML_QuickForm_Page->handle("upload")
#9 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Contribute/Page/Tab.php(302): CRM_Core_Controller->run()
#10 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Contribute/Page/Tab.php(351): CRM_Contribute_Page_Tab->edit()
#11 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Invoke.php(323): CRM_Contribute_Page_Tab->run((Array:4), NULL)
#12 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Invoke.php(72): CRM_Core_Invoke::runItem((Array:13))
#13 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/CRM/Core/Invoke.php(52): CRM_Core_Invoke::_invoke((Array:4))
#14 /var/www/drupal7.civicrm.org/svn/civicrmdemo43/drupal/civicrm.module(456): CRM_Core_Invoke::invoke((Array:4))
#15 [internal function](): civicrm_invoke("contact", "view", "contribution")
#16 /var/www/drupal7.civicrm.org/public/includes/menu.inc(517): call_user_func_array("civicrm_invoke", (Array:3))
#17 /var/www/drupal7.civicrm.org/public/index.php(21): menu_execute_active_handler()
#18

{main}

This occured under version 4.3.8 as well.