我能够使用合并流解决这个问题.如果有人有兴趣，这里是代码.这个想法是在循环中创建一个流数组，并在完成迭代时合并它们:

I was able to pull this off using merge-streams. If anyone's interested, here's the code. The idea is to create an array of streams inside your loop and merge them when finished iterating:

var merge = require('merge-stream');

gulp.task('js', function(){

    // Init vars
    var jsBundleStreams = [];
    var i = 0;

    // Create array of individual bundle streams
    for (var key in buildConfig.bundle) {
        jsBundleStreams[i] = gulp.src(bundleConfig.bundle[key].scripts)
            .pipe(concat(key + '.js'))
            .pipe(gulp.dest('./public/papasteftest/'));
        i++;
    }

    // Merge and return streams
    return merge.apply(this, jsBundleStreams);

});