Hugo site with subdirectory url opens wrong url on preview

Bug description

For Hugo sites with a subdirectory baseURL like https://example.com/blog, running hugo serve makes the site available at http://localhost:1313/blog. However, running quarto preview from the project root opens http://localhost:XXX in a browser rather than http://localhost:XXX/blog, and a 404 error is shown rather than the site home page.

Steps to reproduce

1. git clone --recurse-submodules https://github.com/havijw/quarto-hugo-subdir-bug.git
2. cd quarto-hugo-subdir-bug
3. quarto preview

Expected behavior

Browser opens http://localhost:XXXX/subdir.

Actual behavior

Browser opens http://localhost:XXXX and displays 404 page not found. Navigating to http://localhost:XXXX/subdir displays the site as expected.

Your environment

• MacOS Sonoma 14.1.1
• VSCode
• Python 3.11.6

Quarto check output

$ quarto check

[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.1.1: OK
      Dart Sass version 1.55.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.3.450
      Path: /Applications/quarto/bin

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
      Version: 3.11.6
      Path: /opt/homebrew/opt/python@3.11/bin/python3.11
      Jupyter: 5.3.0
      Kernels: python3

(|) Checking Jupyter engine render....0.00s - Debugger warning: It seems that frozen modules are being used, which may
0.00s - make the debugger miss breakpoints. Please pass -Xfrozen_modules=off
0.00s - to python to disable frozen modules.
0.00s - Note: Debugging will proceed. Set PYDEVD_DISABLE_FILE_VALIDATION=1 to disable this validation.
0.00s - Debugger warning: It seems that frozen modules are being used, which may
0.00s - make the debugger miss breakpoints. Please pass -Xfrozen_modules=off
0.00s - to python to disable frozen modules.
0.00s - Note: Debugging will proceed. Set PYDEVD_DISABLE_FILE_VALIDATION=1 to disable this validation.
[✓] Checking Jupyter engine render....OK

[✓] Checking R installation...........OK
      Version: 4.3.2
      Path: /opt/homebrew/Cellar/r/4.3.2/lib/R
      LibPaths:
        - /opt/homebrew/lib/R/4.3/site-library
        - /opt/homebrew/Cellar/r/4.3.2/lib/R/library
      knitr: (None)
      rmarkdown: (None)

      The rmarkdown package is not available in this R installation.
      Install with install.packages("rmarkdown")