[8.0.1] Cannot fork repository
I cannot fork existing repository.
All i see is this screen.
When i looked up logs i've found this kind of errors:
```
Started POST "//api/v1/builds/register.json" for 127.0.0.1 at 2015-09-24 10:18:05 +0200
ActionController::RoutingError (No route matches [POST] "/api/v1/builds/register.json"):
actionpack (4.1.12) lib/action_dispatch/middleware/debug_exceptions.rb:21:in `call'
actionpack (4.1.12) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
railties (4.1.12) lib/rails/rack/logger.rb:38:in `call_app'
railties (4.1.12) lib/rails/rack/logger.rb:20:in `block in call'
activesupport (4.1.12) lib/active_support/tagged_logging.rb:68:in `block in tagged'
activesupport (4.1.12) lib/active_support/tagged_logging.rb:26:in `tagged'
activesupport (4.1.12) lib/active_support/tagged_logging.rb:68:in `tagged'
railties (4.1.12) lib/rails/rack/logger.rb:20:in `call'
request_store (1.2.0) lib/request_store/middleware.rb:8:in `call'
actionpack (4.1.12) lib/action_dispatch/middleware/request_id.rb:21:in `call'
rack (1.5.5) lib/rack/methodoverride.rb:21:in `call'
rack (1.5.5) lib/rack/runtime.rb:17:in `call'
rack (1.5.5) lib/rack/lock.rb:17:in `call'
rack (1.5.5) lib/rack/sendfile.rb:112:in `call'
railties (4.1.12) lib/rails/engine.rb:514:in `call'
railties (4.1.12) lib/rails/application.rb:144:in `call'
railties (4.1.12) lib/rails/railtie.rb:194:in `public_send'
railties (4.1.12) lib/rails/railtie.rb:194:in `method_missing'
rack (1.5.5) lib/rack/builder.rb:138:in `call'
rack (1.5.5) lib/rack/urlmap.rb:65:in `block in call'
rack (1.5.5) lib/rack/urlmap.rb:50:in `each'
rack (1.5.5) lib/rack/urlmap.rb:50:in `call'
unicorn (4.8.3) lib/unicorn/http_server.rb:576:in `process_client'
unicorn-worker-killer (0.4.3) lib/unicorn/worker_killer.rb:52:in `process_client'
unicorn (4.8.3) lib/unicorn/http_server.rb:670:in `worker_loop'
unicorn (4.8.3) lib/unicorn/http_server.rb:525:in `spawn_missing_workers'
unicorn (4.8.3) lib/unicorn/http_server.rb:536:in `maintain_worker_count'
unicorn (4.8.3) lib/unicorn/http_server.rb:294:in `join'
unicorn (4.8.3) bin/unicorn:126:in `<top (required)>'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/bin/unicorn:23:in `load'
/opt/gitlab/embedded/service/gem/ruby/2.1.0/bin/unicorn:23:in `<main>'
```
issue