Image assets paths not correctly resolved if using URL base in site config

[songololo]

What version of astro are you using?

2.1.2

Are you using an SSR adapter? If so, which one?

None

What package manager are you using?

npm

What operating system are you using?

Mac

What browser are you using?

Chrome

Describe the Bug

I'm trying the new experimental assets optimisation for images.

During development everything works as intended.

When building the site, everything works as intended when using a base path prefix of /.

However, the build breaks if using a base path other than /, e.g. if using test as a basepath, then it tries to use the following style of path:
error ENOENT: no such file or directory, open '/path/to/repo/astro-minimal/dist/test/_astro/ginger_cat.509f05b4.jpeg'

Note that test has been inserted between dist and _astro.

Link to Minimal Reproducible Example

https://github.com/songololo/astro-minimal

Participation

• I am willing to submit a pull request for this issue.

[Princesseuh]

Thank you for submitting this issue! I just renamed the issue to clear up any possible confusion with the old @astrojs/image integration.