What is the meaning of :/ (colon, forward slash) in the 2.0 version of git add --update syntax?

Question

I upgraded Git a couple months ago and since then I\'ve been receiving the following deprecation notice upon attempting git add --update:

Answer 1

The :/ is not the only new syntax, you also have

:!
:(exclude)

Making 'git log' ignore changes for certain paths

So the : signifies that a pathspec is immediately following. Then you have /, also known as the
root directory, or perhaps in this case representing the root of the repository.