Inform the user about an automatically fast-forwarded submodule. The
silent merge behavior was introduced by commit 68d03e4a6e44 ("Implement
automatic fast-forward merge for submodules", 2010-07-07)).
Signed-off-by: Leif Middelschulte <Leif.Middelschulte@gmail.com> Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>