subtree: use "$*" instead of "$@" as appropriate

"$*" is for when you want to concatenate the args together, whitespace-separated; and "$@" is for when you want them to be separate strings. There are several places in subtree that erroneously use $@ when concatenating args together into an error message. For instance, if the args are argv[1]="dead" and argv[2]="beef", then the line die "You must provide exactly one revision. Got: '$@'" surely intends to call 'die' with the argument argv[1]="You must provide exactly one revision. Got: 'dead beef'" however, because the line used $@ instead of $*, it will actually call 'die' with the arguments argv[1]="You must provide exactly one revision. Got: 'dead" argv[2]="beef'" This isn't a big deal, because 'die' concatenates its arguments together anyway (using "$*"). But that doesn't change the fact that it was a mistake to use $@ instead of $*, even though in the end $@ still ended up doing the right thing. Signed-off-by: Luke Shumaker <lukeshu@datawire.io> Signed-off-by: Junio C Hamano <gitster@pobox.com>