Some repository refactors (#17950)

* some repository refactors

* remove unnecessary code

* Fix test

* Remove unnecessary banner

models/repo/fork_test.go

@@ -0,0 +1,32 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package repo
+
+import (
+	"testing"
+
+	"code.gitea.io/gitea/models/unittest"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetUserFork(t *testing.T) {
+	assert.NoError(t, unittest.PrepareTestDatabase())
+
+	// User13 has repo 11 forked from repo10
+	repo, err := GetRepositoryByID(10)
+	assert.NoError(t, err)
+	assert.NotNil(t, repo)
+	repo, err = GetUserFork(repo.ID, 13)
+	assert.NoError(t, err)
+	assert.NotNil(t, repo)
+
+	repo, err = GetRepositoryByID(9)
+	assert.NoError(t, err)
+	assert.NotNil(t, repo)
+	repo, err = GetUserFork(repo.ID, 13)
+	assert.NoError(t, err)
+	assert.Nil(t, repo)
+}