Ensure project discover default branch on Project#show

app/controllers/projects_controller.rb

@@ -57,6 +57,10 @@ class ProjectsController < Projects::ApplicationController
     limit = (params[:limit] || 20).to_i
     @events = @project.events.recent.limit(limit).offset(params[:offset] || 0)
 
+    # Ensure project default branch is set if it possible
+    # Normally it defined on push or during creation
+    @project.discover_default_branch
+
     respond_to do |format|
       format.html do
         if @project.empty_repo?

app/models/project.rb

@@ -312,7 +312,7 @@ class Project < ActiveRecord::Base
   def discover_default_branch
     # Discover the default branch, but only if it hasn't already been set to
     # something else
-    if repository && default_branch.nil?
+    if repository.exists? && default_branch.nil?
       update_attributes(default_branch: self.repository.discover_default_branch)
     end
   end