cli: fix linking with react-router

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/slimy-penguins-care.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Fix for the `--link` flag for `package start` to deduplicate `react-router` and `react-router-dom`.

packages/cli/src/lib/bundler/linkWorkspaces.ts

@@ -48,10 +48,13 @@ export async function createWorkspaceLinkingPlugins(
     }),
     // react and react-dom are always resolved from the target directory
     // Note: this often requires that the linked and target workspace use the same versions of React
-    new bundler.NormalModuleReplacementPlugin(/^react(?:-dom)?$/, resource => {
-      if (!relativePath(linkedRoot.dir, resource.context).startsWith('..')) {
-        resource.context = paths.targetDir;
-      }
-    }),
+    new bundler.NormalModuleReplacementPlugin(
+      /^react(?:-router)?(?:-dom)?$/,
+      resource => {
+        if (!relativePath(linkedRoot.dir, resource.context).startsWith('..')) {
+          resource.context = paths.targetDir;
+        }
+      },
+    ),
   ];
 }