bug: Initial installation attempt to concatenate local 'old_dir'

[mehalter]

Did you check docs and existing issues?

• I have read all the lazy.nvim docs
• I have searched the existing issues of lazy.nvim
• I have searched the existing issues of plugins related to this issue

Neovim version (nvim -v)

NVIM v0.10.0 (github release)

Operating system/version

Arch Linux

Describe the bug

When doing an initial installation with a plugin that configures itself in Lazy a bit as well as being checked out in dev mode it runs into an issue only on the first installation. The message appears that Lazy thinks that the plugin has been added to the runtime path without a directory so when it checks if the plugin's directory has changed it appears to.

Steps To Reproduce

1. mkdir ~/projects, Make a ~/projects folder because we will be using it for dev mode
2. git clone https://github.com/mehalter/lazy_test ~/projects/lazy_test, clone the example plugin
3. rm -rf .repro, Make sure to clean the .repro state because this only happens on a fresh installation
4. nvim -u repro.lua, run the repro.lua configuration and get the error

Expected Behavior

The error shouldn't happen. The directory of the plugin's location shouldn't be changing given the specs.

I get this behavior in this extremely minimal example as well as with AstroNvim when using it in development mode. I honestly cannot replicate this with LazyVim in development mode and I'm honestly not sure why that is.

Repro

-- DO NOT change the paths and don't remove the colorscheme
local root = vim.fn.fnamemodify("./.repro", ":p")

-- set stdpaths to use .repro
for _, name in ipairs({ "config", "data", "state", "cache" }) do
  vim.env[("XDG_%s_HOME"):format(name:upper())] = root .. "/" .. name
end

-- bootstrap lazy
local lazypath = root .. "/plugins/lazy.nvim"
if not vim.loop.fs_stat(lazypath) then
  vim.fn.system({ "git", "clone", "--filter=blob:none", "https://github.com/folke/lazy.nvim.git", lazypath })
end
vim.opt.runtimepath:prepend(lazypath)

-- install plugins
local plugins = {
  { "mehalter/lazy_test", import = "lazy_test" },
}
require("lazy").setup(plugins, {
  root = root .. "/plugins",
  dev = {
    patterns = {
      "lazy_test",
    },
  },
})

[mehalter]

Also for reference, here is a direct link to the test "plugin": https://github.com/mehalter/lazy_test/blob/main/lua/lazy_test/init.lua

All it has is a single file lua/lazy_test/init.lua with the contents:

return {
  { "mehalter/lazy_test", lazy = false, priority = 10000 },
}

[folke]

Thank you for the report. Fixed!