I have the following in my ~/.gitconfig:

	[diff]
		mnemonicPrefix = true

That is supposed to make the a/ and b/ prefix on filenames be changed
to something that clarifies the context --- e.g., i/ and w/ when
comparing the index and worktree.

Alas, when I use "git add -p", "git reset -p", and similar commands, I
get a/ and b/ again.  This makes it harder to remember than it should
be what the hunks shown represent.

Reported by Maarten de Vries on #git.