I want to pad spaces on the left of the user name,

[rebase]
    instructionFormat = %>(10)%al %as %s

However, the above line does not work, it has no padding effect, but if I add any char on the left of %, then it works. Also, %<(10) works in .gitconfig. And the same format works from command line.

git log -n 10 --pretty=format:"%>(10)%al %as %s"