A trailing slash is disappeared from <afile>

[emonkak]

Neovim version (nvim -v)

v0.8.0

Vim (not Nvim) behaves the same?

no, vim 9.0.0655

Operating system/version

Gentoo Linux

Terminal name/version

Alacritty

$TERM environment variable

xterm-256color

Installation

emerge vim

How to reproduce the issue

NVim:

$ nvim -u NONE -es --cmd 'au VimEnter * verbose echo expand("%") expand("<afile>") "\n" | q' foo/
foo/ foo

Vim:

$ vim -u NONE -es --cmd 'au VimEnter * verbose echo expand("%") expand("<afile>") "\n" | q' foo/
foo/ foo/

Expected behavior

Both expand('%') and expand('<afile>') should return 'foo/'. Vim (not Nvim) works as expected.

Actual behavior

expand('<afile>') returns 'foo' without a trailing slash.

Related: #2833

[zeertzjq]

Seems a regression between v0.5.0 and v0.6.0.