record: handle translated prompt correctly
The prompt function would return 'y' or 'n' untranslated. This should
therefore not be compared to _('y') and _('n'). However, it turns out
that prompt could just as well return a good old Boolean.
adding foo
% no signatures
% hg sign 0
Signing 0:e63c23eaa88a
% hg sigs
hgtest 0:e63c23eaa88ae77967edcf4ea194d31167c478b0
% hg sigcheck 0
e63c23eaa88a is signed by:
hgtest