Sourcemaps not ending up in the stream

Please consider this task:

``` javascript
gulp.task("dist-build-css", () => {
/* Compile Sass files using compass to the `css` directory, including sourcemaps and excluding line comments */
return gulp.src([ "includes/sass/**/*.scss", "!includes/sass/**/_*.scss" ])
.pipe(
compass({
sass: "includes/sass",
css: "includes/css",
style: "compressed",
comments: true,
sourcemap: true
})
)
.pipe(gulp.dest("dist/includes/css"))
;
});
```

The problem here is that the sourcemap does not end up in the `dist/includes/css` directory, quite possibly because it's not included in the stream after compass() is done. This will make trouble if I need to further process it, for example if I want to fingerprint the files.

The config options `css` and `sass` are identical to my config.rb file, as instructed. When I set `css` to my dist directory, the sourcemap ends up there as expected, but it's still not included in the stream, so it won't be picked up by any subsequent plugins...

Or should I be using gulp-sourcemap to generate sourcemaps? That'll be trouble as well, since I need to exclude sass includes (starting with `_`) but they do need to go into sourcemaps.

Start with the dist-build-css task and the compass() call, then inspect how the plugin passes files to gulp.dest("dist/includes/css"). Verify whether the generated sourcemap is present in the stream and can be processed by a later plugin; done means it reaches the destination and downstream pipeline.

Written by the indexing model from the issue text.