configdir does not take into account HOME env

[perrin4869]

Problem

I haven't been able to reproduce it reliably outside of github actions, but I am having trouble with the &rtp setting here, which will choose ~/.config/nvim regardless of the value of HOME. This is as opposed to, for example, datadir, which will be correctly added to rtp: /home/runner/work/dotfiles/dotfiles/home/.local/share/nvim

Steps to reproduce

run:

$ HOME=./home nvim --headless -c "echo &rtp" +qa
/home/runner/.config/nvim,/etc/xdg/nvim,/home/runner/work/dotfiles/dotfiles/home/.local/share/nvim/site,/home/runner/work/dotfiles/dotfiles/home/.local/share/nvim/site/pack/*/start/*,/usr/local/share/nvim/site,/usr/share/nvim/site,/home/runner/nvim-nightly/share/nvim/runtime,/home/runner/nvim-nightly/share/nvim/runtime/pack/dist/opt/matchit,/home/runner/nvim-nightly/lib/nvim,/home/runner/work/dotfiles/dotfiles/home/.local/share/nvim/site/pack/*/start/*/after,/usr/share/nvim/site/after,/usr/local/share/nvim/site/after,/home/runner/work/dotfiles/dotfiles/home/.local/share/nvim/site/after,/etc/xdg/nvim/after,/home/runner/.config/nvim/after

Expected behavior

$ HOME=./home nvim --headless -c "echo &rtp" +qa
/home/runner/work/dotfiles/dotfiles/home/.config/nvim,/etc/xdg/nvim,/home/runner/work/dotfiles/dotfiles/home/.local/share/nvim/site,/home/runner/work/dotfiles/dotfiles/home/.local/share/nvim/site/pack/*/start/*,/usr/local/share/nvim/site,/usr/share/nvim/site,/home/runner/nvim-nightly/share/nvim/runtime,/home/runner/nvim-nightly/share/nvim/runtime/pack/dist/opt/matchit,/home/runner/nvim-nightly/lib/nvim,/home/runner/work/dotfiles/dotfiles/home/.local/share/nvim/site/pack/*/start/*/after,/usr/share/nvim/site/after,/usr/local/share/nvim/site/after,/home/runner/work/dotfiles/dotfiles/home/.local/share/nvim/site/after,/etc/xdg/nvim/after,/home/runner/.config/nvim/after

Neovim version (nvim -v)

0.10.0_dev_2913+g5371ed36b

Vim (not Nvim) behaves the same?

irrelevant

Operating system/version

ubuntu-22.04

Terminal name/version

irrelevant

$TERM environment variable

irrelevant

Installation

build from repo

[perrin4869]

ok, I finally figured it out.
inside the github actions environment, XDG_CONFIG_HOME is set to /home/runner/.config by default, and this value will take precedence over HOME if both are set