AMP fix escaped rel (#7045)

if `&amp=1` is used to point to the `amphtml` version of a page it get's escaped causing it to become `&amp=1` this fixes it to stay as `&amp=1`

Closes: #7038 

packages/next-server/server/render.tsx

@@ -450,6 +450,11 @@ export async function renderToHTML(
       await renderOpts.ampValidator(html, pathname)
     }
   }
+
+  if (amphtml || hasAmp) {
+    // fix &amp being escaped for amphtml rel link
+    html = html.replace(/&amp=1/g, '&amp=1')
+  }
   return html
 }
 

test/integration/amphtml/test/index.test.js

@@ -152,6 +152,11 @@ describe('AMP Usage', () => {
       ).toBe('/use-amp-hook?amp=1')
     })
 
+    it('should render link rel amphtml with existing query', async () => {
+      const html = await renderViaHTTP(appPort, '/use-amp-hook?hello=1')
+      expect(html).not.toMatch(/&amp=1/)
+    })
+
     it('should render the AMP page that uses the AMP hook', async () => {
       const html = await renderViaHTTP(appPort, '/use-amp-hook?amp=1')
       const $ = cheerio.load(html)