Add a simple way to rename branch like gh (#15870)

- Update default branch if needed
- Update protected branch if needed
- Update all not merged pull request base branch name
- Rename git branch
- Record this rename work and auto redirect for old branch on ui

Signed-off-by: a1012112796 <1012112796@qq.com>
Co-authored-by: delvh <dev.lh@web.de>

models/branches_test.go

@@ -79,3 +79,52 @@ func getDeletedBranch(t *testing.T, branch *DeletedBranch) *DeletedBranch {
 
 	return deletedBranch
 }
+
+func TestFindRenamedBranch(t *testing.T) {
+	assert.NoError(t, db.PrepareTestDatabase())
+	branch, exist, err := FindRenamedBranch(1, "dev")
+	assert.NoError(t, err)
+	assert.Equal(t, true, exist)
+	assert.Equal(t, "master", branch.To)
+
+	_, exist, err = FindRenamedBranch(1, "unknow")
+	assert.NoError(t, err)
+	assert.Equal(t, false, exist)
+}
+
+func TestRenameBranch(t *testing.T) {
+	assert.NoError(t, db.PrepareTestDatabase())
+	repo1 := db.AssertExistsAndLoadBean(t, &Repository{ID: 1}).(*Repository)
+	_isDefault := false
+
+	err := UpdateProtectBranch(repo1, &ProtectedBranch{
+		RepoID:     repo1.ID,
+		BranchName: "master",
+	}, WhitelistOptions{})
+	assert.NoError(t, err)
+
+	assert.NoError(t, repo1.RenameBranch("master", "main", func(isDefault bool) error {
+		_isDefault = isDefault
+		return nil
+	}))
+
+	assert.Equal(t, true, _isDefault)
+	repo1 = db.AssertExistsAndLoadBean(t, &Repository{ID: 1}).(*Repository)
+	assert.Equal(t, "main", repo1.DefaultBranch)
+
+	pull := db.AssertExistsAndLoadBean(t, &PullRequest{ID: 1}).(*PullRequest) // merged
+	assert.Equal(t, "master", pull.BaseBranch)
+
+	pull = db.AssertExistsAndLoadBean(t, &PullRequest{ID: 2}).(*PullRequest) // open
+	assert.Equal(t, "main", pull.BaseBranch)
+
+	renamedBranch := db.AssertExistsAndLoadBean(t, &RenamedBranch{ID: 2}).(*RenamedBranch)
+	assert.Equal(t, "master", renamedBranch.From)
+	assert.Equal(t, "main", renamedBranch.To)
+	assert.Equal(t, int64(1), renamedBranch.RepoID)
+
+	db.AssertExistsAndLoadBean(t, &ProtectedBranch{
+		RepoID:     repo1.ID,
+		BranchName: "main",
+	})
+}