fix wiki bugs (#1294)

models/wiki.go

 func (repo *Repository) UpdateLocalWiki() error {
 	// Don't pass branch name here because it fails to clone and
 	// checkout to a specific branch when wiki is an empty repository.
-	return UpdateLocalCopyBranch(repo.WikiPath(), repo.LocalWikiPath(), "")
+	var branch = ""
+	if com.IsExist(repo.LocalWikiPath()) {
+		branch = "master"
+	}
+	return UpdateLocalCopyBranch(repo.WikiPath(), repo.LocalWikiPath(), branch)
 }
 
 func discardLocalWikiChanges(localPath string) error {

routers/repo/wiki.go

 		// ctx.Handle(500, "OpenRepository", err)
 		return nil, nil, err
 	}
+	if !wikiRepo.IsBranchExist("master") {
+		return wikiRepo, nil, nil
+	}
+
 	commit, err := wikiRepo.GetBranchCommit("master")
 	if err != nil {
 		ctx.Handle(500, "GetBranchCommit", err)
 	if err != nil {
 		return nil, nil
 	}
+	if commit == nil {
+		return wikiRepo, nil
+	}
 
 	// Get page list.
 	if isViewPage {
 					}
 					pages = append(pages, PageMeta{
 						Name: models.ToWikiPageName(name),
-						URL:  models.ToWikiPageURL(name),
+						URL:  name,
 					})
 				}
 			}
 	if ctx.Written() {
 		return
 	}
+	if entry == nil {
+		ctx.Data["Title"] = ctx.Tr("repo.wiki")
+		ctx.HTML(200, tplWikiStart)
+		return
+	}
 
 	ename := entry.Name()
 	if !markdown.IsMarkdownFile(ename) {
 				}
 				pages = append(pages, PageMeta{
 					Name:    models.ToWikiPageName(name),
-					URL:     models.ToWikiPageURL(name),
+					URL:     name,
 					Updated: c.Author.When,
 				})
 			}
 		return
 	}
 
-	oldWikiPath := ctx.Params(":page")
+	oldWikiPath := models.ToWikiPageURL(ctx.Params(":page"))
 	newWikiPath := models.ToWikiPageURL(form.Title)
 
 	if err := ctx.Repo.Repository.EditWikiPage(ctx.User, oldWikiPath, newWikiPath, form.Content, form.Message); err != nil {
 
 // DeleteWikiPagePost delete wiki page
 func DeleteWikiPagePost(ctx *context.Context) {
-	pageURL := ctx.Params(":page")
+	pageURL := models.ToWikiPageURL(ctx.Params(":page"))
 	if len(pageURL) == 0 {
 		pageURL = "Home"
 	}