wrong journal entries created over a taxable services using hr_expense

journal entries created from hr_expense module when the expense line has service product with default tax(include/exclude).

Problem:
1. a service product, contains purchase tax/taxes(can be expense, tax code and base code should be negative)
2. create an entry of expense for this service product
3. confirm, validate the expense, journal entries created are wrong

Solution:
the tax code and base code sign was multiplied to the "price" of the journal items, which is wrong, because
it is basically used to assign into debit/credit column, tax/base code sign it should be assigned only to "tax_amount"