[Localization] string not updated

[jamarat]

While translating Fructose/Calculate I found wrong string to be translated
(in the .po file):
"sinh(x), return the hyperbolic tangent of x. Given by sinh(x) / cosh(x)"
(http://translate.sugarlabs.org/pl/fructose/calculate-activity.po?item=64&vi
ew_mode=translate)

I checked that it was fixed in source code about a year ago:
http://bugs.sugarlabs.org/ticket/1722

I did both "scan files" and "template update" but nothing changed, there is
still wrog def of tanh in the .po file.

What is wrong?
Jakub