_ipn_process_transaction() misses parameters

_ipn_process_transaction() takes an array with parameters (the $params array). It later calls $ipn->completeTransaction(). But instead of supplying those parameters to it, _ipn_process_transaction() builds a new array with parameters (the $input array) that it then passes to $ipn->completeTransaction(). In this process some of the parameters that were passed to _ipn_process_transaction() never get passed to $ipn->completeTransaction().

One of these parameters is the transaction fee. So, for example, if we do:

$result = civicrm_api3('Contribution', 'completetransaction', array(
'sequential' => 1,
'id' => 305,
'trxn_id' => 'ch_17Jg51ISj0NDf41qft8dc0',
'fee_amount' => 0.49
));

the 'fee_amount' parameter doesn't get passed to $ipn->completeTransaction() and so doesn't get written to the database.

Patch that fixes the problem for the 'fee_amount' parameter: https://github.com/civicrm/civicrm-core/pull/7479