postProcess hook sometimes not called on Contribution page

When the 'Use a confirmation page' is unchecked on a contribution page, the postProcess hook is not called for that page. This is because the postProcess function for the main contribution page never returns as it then redirects straight to the thank-you page.

Here is the fix: File CRM/Contribute/Form/Contribution/Main, line 1412, replace:
// should we skip the confirm page?
if (!CRM_Utils_Array::value('is_confirm_enabled', $this->_values)) {
// build the confirm page

With:
// should we skip the confirm page?
if (!CRM_Utils_Array::value('is_confirm_enabled', $this->_values)) {
// call postProcess hook before leaving since we will not return
$this->postProcessHook();

// build the confirm page