Implement final review comments from @DouweM and @rymai

- Have `Uniquify` take a block instead of a Proc/function. This is more
  idiomatic than passing around a function in Ruby.

- Block a user before moving their issues to the ghost user. This avoids a data
  race where an issue is created after the issues are migrated to the ghost user,
  and before the destroy takes place.

- No need to migrate issues (to the ghost user) in a transaction, because
  we're using `update_all`

- Other minor changes

1 files changed, 1 insertions, 1 deletions

diff --git a/app/models/namespace.rb b/app/models/namespace.rb
index 8cc3c1473e2..3137dd32f93 100644
--- a/app/models/namespace.rb
+++ b/app/models/namespace.rb
@@ -99,7 +99,7 @@ class Namespace < ActiveRecord::Base
       path = "blank" if path.blank?
 
       uniquify = Uniquify.new
-      uniquify.string(path, -> (s) { Namespace.find_by_path_or_name(s) })
+      uniquify.string(path) { |s| Namespace.find_by_path_or_name(s) }
     end
   end