Before this commit:
If there is no subject for message, it effectively displays "False" in case of
void subject.
After this commit:
If there is no subject for message, it will not display "False" in case of void
subject.
Tasks-2156170
closesodoo/odoo#68243
X-original-commit: 4b2f0ddcbe859ec8453e537aec9d5b0685876eca
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>