Two files exported when trying to rename filename.

Hi,

Anyone tried to rename output file to `some_style.min.css`?
I am trying to change the output file name with the following task:

```
gulp.task('compass', false, function () {
return gulp.src([SASS_PATH + '/**/*.scss')
.pipe(changed(DEST_PATH, {extension: '.min.css'}))
.pipe(compass({
config_file: 'config.rb',
css: DEST_PATH,
sass: SASS_PATH,
style: 'compressed',
debug: false,
require: ['susy'],
}))
.pipe($.autoprefixer())
.pipe($.rename({
suffix: ".min"
}))
.pipe(gulp.dest(DEST_PATH))
.pipe(reload({stream: true}));
});
```

When I run the above task, it exports `some_style.css` as well as `some_style.min.css`.
How can I export **only** `some_style.min.css` file?

Start with the shown gulp 'compass' task and trace the output through compass, autoprefixer, rename, and gulp.dest. Reproduce the task with the sample filename, then verify that completion leaves only some_style.min.css in DEST_PATH.

Written by the indexing model from the issue text.