Do not show unnecessary message during server startup

Currently, `Exiting` is showed during server startup.

```
./bin/rails s
=> Booting Puma
=> Rails 6.0.0.alpha application starting in development
=> Run `rails server --help` for more startup options
Exiting
Puma starting in single mode...
* Version 3.11.2 (ruby 2.5.0-p0), codename: Love Song
```

This is because processing at server stop is passed as a block, and
`Rack::Serve#start` receives a block and executes it during startup processing.
https://github.com/rack/rack/blob/50db1ffdf8b98503fb7c6e6648622b5d7d78d58e/lib/rack/server.rb#L258

In order to avoid this, stop processing is passed as argument.

1 files changed, 5 insertions, 6 deletions

diff --git a/railties/lib/rails/commands/server/server_command.rb b/railties/lib/rails/commands/server/server_command.rb
index 64fb912b51..8588e2fd64 100644
--- a/railties/lib/rails/commands/server/server_command.rb
+++ b/railties/lib/rails/commands/server/server_command.rb
@@ -43,15 +43,15 @@ module Rails
       ENV["RAILS_ENV"] ||= options[:environment]
     end
 
-    def start
+    def start(after_stop_callback = nil)
       trap(:INT) { exit }
       create_tmp_directories
       setup_dev_caching
       log_to_stdout if options[:log_stdout]
 
-      super
+      super()
     ensure
-      yield
+      after_stop_callback.call if after_stop_callback
     end
 
     def serveable? # :nodoc:
@@ -157,9 +157,8 @@ module Rails
 
           if server.serveable?
             print_boot_information(server.server, server.served_url)
-            server.start do
-              say "Exiting" unless options[:daemon]
-            end
+            after_stop_callback = -> { say "Exiting" unless options[:daemon] }
+            server.start(after_stop_callback)
           else
             say rack_server_suggestion(using)
           end