Revert "[Rails5] Set request.format in commits_controller"

This reverts commit 6da19415.

# Conflicts:
#	app/controllers/projects/commits_controller.rb

app/controllers/projects/commits_controller.rb

@@ -12,7 +12,6 @@ class Projects::CommitsController < Projects::ApplicationController
   before_action :assign_ref_vars, except: :commits_root
   before_action :authorize_download_code!
   before_action :set_commits, except: :commits_root
-  before_action :set_request_format, only: :show
 
   def commits_root
     redirect_to project_commits_path(@project, @project.default_branch)
@@ -71,19 +70,6 @@ class Projects::CommitsController < Projects::ApplicationController
     @commits = set_commits_for_rendering(@commits)
   end
 
-  # Rails 5 sets request.format from the extension.
-  # Explicitly set to :html.
-  def set_request_format
-    request.format = :html if set_request_format?
-  end
-
-  # Rails 5 sets request.format from extension.
-  # In this case if the ref ends with `.atom`, it's expected to be the html response,
-  # not the atom one. So explicitly set request.format as :html to act like rails4.
-  def set_request_format?
-    request.format.to_s == "text/html" || @commits.ref.ends_with?("atom")
-  end
-
   def whitelist_query_limiting
     Gitlab::QueryLimiting.whitelist('https://gitlab.com/gitlab-org/gitlab-ce/issues/42330')
   end