Modified migration conflict message to remove the string concatenation.

railties/lib/rails/generators/actions/create_migration.rb

@@ -54,9 +54,9 @@ def on_conflict_behavior(&block)
             say_status :skip, :yellow
           else
             say_status :conflict, :red
-            raise Error, "Another migration is already named #{migration_file_name}: " +
-                         "#{existing_migration}. Use --force to replace this migration" +
-                         " or --skip to ignore conflicted file."
+            raise Error, "Another migration is already named #{migration_file_name}: " \
+              "#{existing_migration}. Use --force to replace this migration " \
+              "or --skip to ignore conflicted file."
           end
         end