Can't change default branch

Omnibus CE 7.10

Not able to change default branch on existing project organization namespace be me listed as owner.
I can see the branch and select the branch in the dropdown, but when I click Save, the change is not saved, but no error messages are logged that I am aware. I can change other details like the description for the project and those changes are saved.

/var/log/gitlab/gitlab-rails/production.log lists the following in regards to event, some details scrubbed.

Started PATCH "/sais/cloudformation_templates" for x.x.x.x at 2015-04-30 18:25:10 +0000
Processing by ProjectsController#update as JS
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"[FILTERED]", "project"=>{"name"=>"cloudformation_templates", "description"=>"Cloudformation Templates to be deployed to S3 bucket for deploying of servers, or creating new Gold Images for deployment.", "default_branch"=>"development", "visibility_level"=>"0", "tag_list"=>"", "issues_enabled"=>"1", "merge_requests_enabled"=>"1", "wiki_enabled"=>"1", "snippets_enabled"=>"0"}, "commit"=>"Save changes", "namespace_id"=>"sais", "id"=>"cloudformation_templates"}
Completed 200 OK in 511ms (Views: 3.3ms | ActiveRecord: 7.0ms)
Started GET "/sais/cloudformation_templates/edit" for x.x.x.x at 2015-04-30 18:25:11 +0000
Processing by ProjectsController#edit as HTML
  Parameters: {"namespace_id"=>"sais", "id"=>"cloudformation_templates"}
Completed 200 OK in 129ms (Views: 86.3ms | ActiveRecord: 12.5ms)

As you can see default branch is set to development, however it does not stick and keeps reverting to master branch.

Do not have issue with a new project, only a certain existing project.

Sounds like you’re just getting some cached results. Try clearing it via gitlab-rake cache:clear

Thank you. I will keep that in mind if it happens again. I hope your reply will be a help for those who have similar issues.
To clear the issue I deleted the repo and recreated it.

Maybe it is unrelated. For the indexing
I could not change default branch. I was helped by the removal of the incorrect ‘HEAD’ branch.