The _(doctype) inside get_message is removed from the .format() method. The reason is that _(doctype) would attempt to translate the doctype itself, which is generally not required since the doctypes in doctype_list are system-level terms. The main string "{0} has been submitted successfully" should be translated, and then it should receive the doctype name as an argument.
(cherry picked from commit 804558e5bf)
f70506fc92