Git diff --no-index --no-prefix output loses leading slash in paths

As of 2.17.1, `git diff --no-index --no-prefix relative/path /absolute/path` produces the following:

diff --git relative/path absolute/path

index XXXXXXX..YYYYYYY ZZZZZZ

--- relative/path
+++ absolute/path

The leading slash on `absolute/path` is lost. This is unfortunate; my use case is a diff highlighter that parses and reformats paths so that code editors can autodetect them and link to the files. 

Would the maintainers please consider fixing the output to preserve absolute paths?

Thank you,
George King