外部タグを分離 (#419) (#420)

**本番 DB のバックアップをかならずすること**

Reviewed-on: #420
Co-authored-by: miteruzo <miteruzo@naver.com>

frontend/src/lib/prefetchers.test.ts

@@ -137,4 +137,19 @@ describe ('prefetchForURL', () => {
     expect (tagsApi.fetchTags).not.toHaveBeenCalled ()
     expect (wikiApi.fetchWikiPages).not.toHaveBeenCalled ()
   })
+
+  it ('prefetches external tag post history without treating it as an internal tag', async () => {
+    await prefetchForURL (
+	qc (),
+	'http://localhost/posts/changes?external_tag=12&page=2&limit=50',
+    )
+
+    expect (postsApi.fetchPostChanges).toHaveBeenCalledWith ({
+      externalTag: '12',
+      page:        2,
+      limit:       50,
+    })
+
+    expect (tagsApi.fetchTag).not.toHaveBeenCalled ()
+  })
 })