Exit with non-zero status when db:create fails

* If the create task fails for a reason other than the database already
  existing, processing should end. This is indicated by a non-zero exit
  status.
* Since the backtrace is already printed to screen, we forgo printing it
  again by using an explicit call to `exit`.
* ⚠️ This modifies the behavior of the db:create task slightly in
  that the stack trace is no longer printed by default. If the `--trace`
  option is used, it will print the trace _after_ the error message.

activerecord/lib/active_record/tasks/database_tasks.rb

@@ -94,8 +94,9 @@ module ActiveRecord
       rescue DatabaseAlreadyExists
         $stderr.puts "#{configuration['database']} already exists"
       rescue Exception => error
-        $stderr.puts error, *(error.backtrace)
+        $stderr.puts error
         $stderr.puts "Couldn't create database for #{configuration.inspect}"
+        raise
       end
 
       def create_all

activerecord/test/cases/tasks/postgresql_rake_test.rb

@@ -60,7 +60,7 @@ module ActiveRecord
       $stderr.expects(:puts).
         with("Couldn't create database for #{@configuration.inspect}")
 
-      ActiveRecord::Tasks::DatabaseTasks.create @configuration
+      assert_raises(Exception) { ActiveRecord::Tasks::DatabaseTasks.create @configuration }
     end
 
     def test_create_when_database_exists_outputs_info_to_stderr

activerecord/test/cases/tasks/sqlite_rake_test.rb

@@ -53,7 +53,7 @@ module ActiveRecord
       $stderr.expects(:puts).
         with("Couldn't create database for #{@configuration.inspect}")
 
-      ActiveRecord::Tasks::DatabaseTasks.create @configuration, '/rails/root'
+      assert_raises(Exception) { ActiveRecord::Tasks::DatabaseTasks.create @configuration, '/rails/root' }
     end
   end
 

railties/test/application/rake/dbs_test.rb

@@ -66,6 +66,23 @@ module ApplicationTests
         end
       end
 
+      def with_bad_permissions
+        Dir.chdir(app_path) do
+          set_database_url
+          FileUtils.chmod("-w", "db")
+          yield
+          FileUtils.chmod("+w", "db")
+        end
+      end
+
+      test 'db:create failure because bad permissions' do
+        with_bad_permissions do
+          output = `bin/rake db:create 2>&1`
+          assert_match /Couldn't create database/, output
+          assert_equal 1, $?.exitstatus
+        end
+      end
+
       test 'db:drop failure because database does not exist' do
         Dir.chdir(app_path) do
           output = `bin/rake db:drop 2>&1`