git-fetch: Fix "argument list too long"

git-fetch: Fix "argument list too long"

If $ls_remote_result was too long,

    git-fetch--tool -s pick-rref "$rref" "$ls_remote_result"

in git-fetch will fail with "argument list too long".

This patch fixes git-fetch--tool and git-fetch by passing
$ls_remote_result via stdin.

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Junio C Hamano <junkio@cox.net>