standard "a/" and "b/" depending on what is being compared. When
this configuration is in effect, reverse diff output also swaps
the order of the prefixes:
- If set, 'git diff' does not show any source or destination prefix.
compares the (i)ndex and the (w)ork tree;
`git diff --no-index a b`;;
compares two non-git things (1) and (2).
+ If set, 'git diff' does not show any source or destination prefix.
The number of files to consider when performing the copy/rename
detection; equivalent to the 'git diff' option '-l'.