command-list.sh, retired in the previous patch, was the only
consumer of the "common" tag, so drop this now-unnecessary
attribute.
before:
git-add mainporcelain common worktree
after:
git-add mainporcelain worktree
Helped-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Sébastien Guimmara <sebastien.guimmara@gmail.com> Reviewed-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>