Instead of use the original string by default.
Currently odoo export a PO translation file using the logic:
"If there is not a translation then use the source."
This generate a false 100% of file translated for tools based on PO
files.
This commit change this logic to:
"If there is not a translation then use empty string."
Odoo import a PO translation file supporting empty string because
if a item is empty string odoo use the original source.
Closes#17925
Moises Lopez - https://www.vauxoo.com/
eb90eb42ce