Commit with a generic commit message based on the first staged filename and action performed on the file.
For cases, when you possibly couldn't come up with a better commit message or it simply doesn't matter.
$ git status -s
A image.png
$ git-commit-auto-message
[master a61951a] add image.png
1 file changed, 0 insertions(+), 0 deletions(-)
create mode 100644 my-image.png
$ git mv image.png hello.png
$ git-commit-auto-message
[master b48759f] rename image.png to hello.png
1 file changed, 0 insertions(+), 0 deletions(-)
rename image.png => hello.png (100%)
$ git log
b48759f rename image.png to hello.png
a61951a add image.png