SSG pages with route rewrites request wrong files from _next/data

### Link to the code that reproduces this issue https://github.com/fmacherey/poc-ssg ### To Reproduce 1. yarn build && yarn start 2. open page `localhost:3000/lexikon/a` 3. open dev tools, filter network for "next/data" 4. navigate between "a", "b" and "c" ### Current vs. Expected behavior You'll see several network requests for the static ssr json files e.g. ``` http://localhost:3000/_next/data/<BUILD_ID>/dict/b.json?character=b http://localhost:3000/_next/data/<BUILD_ID>/lexikon/b.json?character=b ``` The first GET request is fine and correct, but the secondly listed HEAD request leads to a 404 Not Found. Expected: the HEAD request should not occur or at least going correctly to the internal file "dict/b.json" and not the rewritten path (see next.config) ### Provide environment information ```sh Operating System: Platform: darwin Arch: arm64 Version: Darwin Kernel Version 23.4.0: Wed Feb 21 21:45:49 PST 2024; root:xnu-10063.101.15~2/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: 8.15.1 Relevant Packages: next: 14.2.0-canary.17 // Latest available version is detected (14.2.0-canary.17). eslint-config-next: 14.1.3 react: 18.2.0 react-dom: 18.2.0 typescript: 5.4.2 Next.js Config: output: N/A ✨ Done in 1.45s. ``` ### Which area(s) are affected? (Select all that apply) Data fetching (gS(S)P, getInitialProps) ### Which stage(s) are affected? (Select all that apply) next build (local), next start (local) ### Additional context _No response_