how to omit rename file when commit

For example there are a file a.c at git repository.
use
git mv a.c b.c

git status:
# On branch master
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#       renamed:    a.c -> b.c

If we don't want to stage this change at this commit,  what can I do?