add test case

[sokra]

fixes #30567

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall decrease ✓

	vercel/next.js canary	vercel/next.js test/external-css	Change
buildDuration	22.8s	23.3s	⚠️ +516ms
buildDurationCached	4.5s	4.5s	⚠️ +76ms
nodeModulesSize	339 MB	339 MB	-6 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	vercel/next.js test/external-css	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.841	3.892	⚠️ +0.05
/ avg req/sec	650.89	642.29	⚠️ -8.6
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	2.21	2.052	-0.16
/error-in-render avg req/sec	1131.08	1218.11	+87.03

Client Bundles (main, webpack, commons)

	vercel/next.js canary	vercel/next.js test/external-css	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	28.4 kB	28.4 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	72.2 kB	72.2 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js test/external-css	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js test/external-css	Change
_app-HASH.js gzip	1.37 kB	1.37 kB	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	327 B	327 B	✓
dynamic-HASH.js gzip	2.38 kB	2.38 kB	✓
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	635 B	635 B	✓
image-HASH.js gzip	4.45 kB	4.45 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	1.87 kB	1.87 kB	✓
routerDirect..HASH.js gzip	321 B	321 B	✓
script-HASH.js gzip	383 B	383 B	✓
withRouter-HASH.js gzip	318 B	318 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	13.3 kB	13.3 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js test/external-css	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js test/external-css	Change
index.html gzip	532 B	532 B	✓
link.html gzip	545 B	545 B	✓
withRouter.html gzip	527 B	527 B	✓
Overall change	1.6 kB	1.6 kB	✓

---

Default Build with SWC (Increase detected ⚠️)

General Overall decrease ✓

	vercel/next.js canary	vercel/next.js test/external-css	Change
buildDuration	25.5s	25.1s	-427ms
buildDurationCached	4.5s	4.5s	-69ms
nodeModulesSize	339 MB	339 MB	-6 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	vercel/next.js test/external-css	Change
/ failed reqs	0	0	✓
/ total time (seconds)	4.056	3.972	-0.08
/ avg req/sec	616.44	629.48	+13.04
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	2.228	2.137	-0.09
/error-in-render avg req/sec	1122.03	1169.78	+47.75

Client Bundles (main, webpack, commons)

	vercel/next.js canary	vercel/next.js test/external-css	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	28.6 kB	28.6 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	72.5 kB	72.5 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js test/external-css	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js test/external-css	Change
_app-HASH.js gzip	1.35 kB	1.35 kB	✓
_error-HASH.js gzip	180 B	180 B	✓
amp-HASH.js gzip	305 B	305 B	✓
css-HASH.js gzip	321 B	321 B	✓
dynamic-HASH.js gzip	2.38 kB	2.38 kB	✓
head-HASH.js gzip	342 B	342 B	✓
hooks-HASH.js gzip	622 B	622 B	✓
image-HASH.js gzip	4.47 kB	4.47 kB	✓
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	1.91 kB	1.91 kB	✓
routerDirect..HASH.js gzip	314 B	314 B	✓
script-HASH.js gzip	375 B	375 B	✓
withRouter-HASH.js gzip	309 B	309 B	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	13.2 kB	13.2 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js test/external-css	Change
_buildManifest.js gzip	459 B	459 B	✓
Overall change	459 B	459 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js test/external-css	Change
index.html gzip	533 B	533 B	✓
link.html gzip	546 B	546 B	✓
withRouter.html gzip	527 B	527 B	✓
Overall change	1.61 kB	1.61 kB	✓

Commit: e2a59cf