Edit contribution : wrong decimal separator on total_amount

I am using civicrm 4.7.14 with a comma as decimal separator (config)

If i renew a membership with a delayed payment a new contribution (pending) is created.
Next, if i want to edit this contribution the total_amount is set with a "dot" separator.
(this field is not editable in that use case)

In consequence, submit the form is impossible and throw an error : " enter a valid amount "

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See attached patch.