Errors in zola serve with hard_link_static = true

[Keats]

From #1217 (comment) by @koitsu

Can confirm: the issue only happens when using hard_link_static = true, and happens regardless if you have any static assets or not. It's as easy as this:

Terminal 1: make sure you have a zola site that is working/building correctly
Terminal 2: zola serve + whatever args (sans -f)
Terminal 1: modify an .md file -- literally just open it up in vi, change nothing, and write it
Terminal 2: Zola begins to report bizarre and unhelpful errors (I sure wish it showed what file/directory it was accessing that resulted in errno EEXIST).

Demonstration of above:

$ zola serve -i 0.0.0.0 -p 1111
Building site...
Checking all internal links with anchors.
> Successfully checked 0 internal link(s) with anchors.
-> Creating 1 pages (0 orphan) and 1 sections
Done in 124ms.

Listening for changes in /home/jdc/blog20{config.toml, content, sass, static, templates}
Press Ctrl+C to stop

Web server is available at http://0.0.0.0:1111

Change detected @ 2022-05-30 20:38:37
-> Content changed /home/jdc/blog20/content/blog/2022-05-30-welcome-to-dumb.md
Checking all internal links with anchors.
> Successfully checked 0 internal link(s) with anchors.
-> Creating 1 pages (0 orphan) and 1 sections
Failed to build the site
Error: File exists (os error 17)
Done in 6ms.

[Raymi306]

run touch $FILENAME to save a few key strokes when causing failures