test harness: Fix the pretty-printer's padding implementation.
test harness: Fix the pretty-printer's padding implementation.

The new implementation is less efficient but definitely correct.

phy1729/zsh-syntax-highlighting,phy1729/zsh-syntax-highlighting,P71/zsh-syntax-highlighting,P71/zsh-syntax-highlighting,zsh-users/zsh-syntax-highlighting,zsh-users/zsh-syntax-highlighting