fix grep search

Author: wxiaoguang

routers/web/repo/search.go

@@ -70,7 +70,7 @@ func Search(ctx *context.Context) {
 		res, err := git.GrepSearch(ctx, ctx.Repo.GitRepo, prepareSearch.Keyword, git.GrepOptions{
 			ContextLineNumber: 1,
 			IsFuzzy:           prepareSearch.IsFuzzy,
-			RefName:           git.RefNameFromBranch(ctx.Repo.BranchName).String(), // BranchName should be default branch or the first existing branch
+			RefName:           git.RefNameFromBranch(ctx.Repo.Repository.DefaultBranch).String(), // BranchName should be default branch or the first existing branch
 			PathspecList:      indexSettingToGitGrepPathspecList(),
 		})
 		if err != nil {

routers/web/web.go

@@ -1592,7 +1592,7 @@ func registerRoutes(m *web.Router) {
 		m.Get("/watchers", repo.Watchers)
 		m.Get("/search", reqUnitCodeReader, repo.Search)
 		m.Post("/action/{action}", reqSignIn, repo.Action)
-	}, optSignIn, context.RepoAssignment, context.RepoRef())
+	}, optSignIn, context.RepoAssignment)
 
 	common.AddOwnerRepoGitLFSRoutes(m, optSignInIgnoreCsrf, lfsServerEnabled) // "/{username}/{reponame}/{lfs-paths}": git-lfs support