notFound() does not replace robots tag

[fmacherey]

Link to the code that reproduces this issue

https://codesandbox.io/p/devbox/app-meta-robots-issue-66fwcs?layout=%257B%2522sidebarPanel%2522%253A%2522EXPLORER%2522%252C%2522rootPanelGroup%2522%253A%257B%2522direction%2522%253A%2522horizontal%2522%252C%2522contentType%2522%253A%2522UNKNOWN%2522%252C%2522type%2522%253A%2522PANEL_GROUP%2522%252C%2522id%2522%253A%2522ROOT_LAYOUT%2522%252C%2522panels%2522%253A%255B%257B%2522type%2522%253A%2522PANEL_GROUP%2522%252C%2522contentType%2522%253A%2522UNKNOWN%2522%252C%2522direction%2522%253A%2522vertical%2522%252C%2522id%2522%253A%2522clyrb3nwj00073b6sqq6xm9do%2522%252C%2522sizes%2522%253A%255B70%252C30%255D%252C%2522panels%2522%253A%255B%257B%2522type%2522%253A%2522PANEL_GROUP%2522%252C%2522contentType%2522%253A%2522EDITOR%2522%252C%2522direction%2522%253A%2522horizontal%2522%252C%2522id%2522%253A%2522EDITOR%2522%252C%2522panels%2522%253A%255B%257B%2522type%2522%253A%2522PANEL%2522%252C%2522contentType%2522%253A%2522EDITOR%2522%252C%2522id%2522%253A%2522clyrb3nwj00023b6sotsfakd2%2522%257D%255D%257D%252C%257B%2522type%2522%253A%2522PANEL_GROUP%2522%252C%2522contentType%2522%253A%2522SHELLS%2522%252C%2522direction%2522%253A%2522horizontal%2522%252C%2522id%2522%253A%2522SHELLS%2522%252C%2522panels%2522%253A%255B%257B%2522type%2522%253A%2522PANEL%2522%252C%2522contentType%2522%253A%2522SHELLS%2522%252C%2522id%2522%253A%2522clyrb3nwj00043b6sbe2sqt30%2522%257D%255D%252C%2522sizes%2522%253A%255B100%255D%257D%255D%257D%252C%257B%2522type%2522%253A%2522PANEL_GROUP%2522%252C%2522contentType%2522%253A%2522DEVTOOLS%2522%252C%2522direction%2522%253A%2522vertical%2522%252C%2522id%2522%253A%2522DEVTOOLS%2522%252C%2522panels%2522%253A%255B%257B%2522type%2522%253A%2522PANEL%2522%252C%2522contentType%2522%253A%2522DEVTOOLS%2522%252C%2522id%2522%253A%2522clyrb3nwj00063b6snoopsfrp%2522%257D%255D%252C%2522sizes%2522%253A%255B100%255D%257D%255D%252C%2522sizes%2522%253A%255B50%252C50%255D%257D%252C%2522tabbedPanels%2522%253A%257B%2522clyrb3nwj00023b6sotsfakd2%2522%253A%257B%2522tabs%2522%253A%255B%257B%2522id%2522%253A%2522clyrb3nwj00013b6slgz5aiu0%2522%252C%2522mode%2522%253A%2522permanent%2522%252C%2522type%2522%253A%2522FILE%2522%252C%2522filepath%2522%253A%2522%252FREADME.md%2522%257D%255D%252C%2522id%2522%253A%2522clyrb3nwj00023b6sotsfakd2%2522%252C%2522activeTabId%2522%253A%2522clyrb3nwj00013b6slgz5aiu0%2522%257D%252C%2522clyrb3nwj00063b6snoopsfrp%2522%253A%257B%2522tabs%2522%253A%255B%257B%2522id%2522%253A%2522clyrb3nwj00053b6sdvyjnp14%2522%252C%2522mode%2522%253A%2522permanent%2522%252C%2522type%2522%253A%2522TASK_PORT%2522%252C%2522taskId%2522%253A%2522dev%2522%252C%2522port%2522%253A3000%252C%2522path%2522%253A%2522%252F%2522%257D%255D%252C%2522id%2522%253A%2522clyrb3nwj00063b6snoopsfrp%2522%252C%2522activeTabId%2522%253A%2522clyrb3nwj00053b6sdvyjnp14%2522%257D%252C%2522clyrb3nwj00043b6sbe2sqt30%2522%253A%257B%2522tabs%2522%253A%255B%257B%2522id%2522%253A%2522clyrb3nwj00033b6sjdk6862c%2522%252C%2522mode%2522%253A%2522permanent%2522%252C%2522type%2522%253A%2522TASK_LOG%2522%252C%2522taskId%2522%253A%2522dev%2522%257D%255D%252C%2522id%2522%253A%2522clyrb3nwj00043b6sbe2sqt30%2522%252C%2522activeTabId%2522%253A%2522clyrb3nwj00033b6sjdk6862c%2522%257D%257D%252C%2522showDevtools%2522%253Atrue%252C%2522showShells%2522%253Atrue%252C%2522showSidebar%2522%253Atrue%252C%2522sidebarPanelSize%2522%253A15%257D

To Reproduce

1. open Sandbox
2. inspect page
3. find two entries in the header

Current vs. Expected behavior

notFound is replacing the existing meta robots entry with noindex, so there is only one entry in the page

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 23.5.0: Wed May  1 20:14:38 PDT 2024; root:xnu-10063.121.3~5/RELEASE_ARM64_T6020
  Available memory (MB): 32768
  Available CPU cores: 12
Binaries:
  Node: 20.9.0
  npm: 10.1.0
  Yarn: 1.22.19
  pnpm: 9.1.2
Relevant Packages:
  next: 14.2.5 // Latest available version is detected (14.2.5).
  eslint-config-next: 14.2.5
  react: 18.3.1
  react-dom: 18.3.1
  typescript: 5.4.5
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Metadata, Navigation

Which stage(s) are affected? (Select all that apply)

next dev (local), next build (local), next start (local)

Additional context

No response

[fmacherey]

I just found out, when I call notFound() inside generateMetadata(), then the meta attributes don't get appended into the DOM. But not sure, if this is an feature?