appview: repo/index: show fork button only to repo owners

also do GetForkInfo only if repo-owner

appview/pages/pages.go

···
 	CommitsTrunc  []*object.Commit
 	TagsTrunc     []*types.TagReference
 	BranchesTrunc []types.Branch
-	ForkInfo      types.ForkInfo
+	ForkInfo      *types.ForkInfo
 	types.RepoIndexResponse
 	HTMLReadme         template.HTML
 	Raw                bool

appview/pages/templates/repo/index.html

···
             {{ end }}
         </optgroup>
     </select>
-    {{ if .ForkInfo.IsFork }}
+    {{ $isOwner := and .LoggedInUser (eq .LoggedInUser.Did .RepoInfo.OwnerDid) }}
+    {{ if and $isOwner .ForkInfo }}
         {{ $disabled := "" }}
         {{ $title := "" }}
         {{ if eq .ForkInfo.Status 0 }}

appview/state/repo.go

···
 	user := s.oauth.GetUser(r)
 	repoInfo := f.RepoInfo(s, user)
 
-	forkInfo, err := getForkInfo(repoInfo, s, f, w, user)
-	if err != nil {
-		log.Printf("Failed to fetch fork information: %v", err)
-		return
+	var forkInfo *types.ForkInfo
+	if user != nil && user.Did == repoInfo.OwnerDid {
+		forkInfo, err = getForkInfo(repoInfo, s, f, w, user)
+		if err != nil {
+			log.Printf("Failed to fetch fork information: %v", err)
+			return
+		}
 	}
 
 	s.pages.RepoIndexPage(w, pages.RepoIndexParams{
···
 		RepoIndexResponse:  result,
 		CommitsTrunc:       commitsTrunc,
 		TagsTrunc:          tagsTrunc,
-		ForkInfo:           *forkInfo,
+		ForkInfo:           forkInfo,
 		BranchesTrunc:      branchesTrunc,
 		EmailToDidOrHandle: EmailToDidOrHandle(s, emails),
 	})