Just as was done in 0008d12284 (submodule: prefix die messages with
'fatal', 2021-07-10) for 'git-submodule.sh', make the 'die' messages
outputed by 'git-subtree.sh' more in line with the rest of the code base
by prefixing them with "fatal: ", and do not capitalize their first
letter.
Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
5626a9e2a9