Gulp手表不会覆盖文件

Question

当我启动gulp时会生成文件，但是当它进入监视模式时，会理解存在更改但不会覆盖文件：

我的gulp样本

var argv = require('yargs').argv;
var gulp = require('gulp');
var gulpif = require('gulp-if');
var uglify = require('gulp-uglify');

var dependencies = [
    'core-js/client/*.min.js',
    'zone.js/dist/zone.js',
    'reflect-metadata/Reflect.js',
    'systemjs/dist/system.src.js',
    'rxjs/**/*.js',
    '@angular/**/*.js',
    'angular2-in-memory-web-api/*.js',
];

var modules = [
    // Example: 'iconv-lite/**/*',
];

........
gulp.task("javascript", () => {
    return gulp.src([
        './bower_components/jquery/dist/jquery.min.js',
        './bower_components/bootstrap/dist/js/bootstrap.min.js',
    ])
        .pipe(gulp.dest("./build/js"))
});

gulp.task('styles', () => {
    var postcss      = require('gulp-postcss');
    var autoreset    = require('postcss-autoreset');
    var simplevars   = require('postcss-simple-vars');
    var nested       = require('postcss-nested');
    var lost         = require('lost');
    var cssnext      = require('postcss-cssnext');
    var processors = [
        simplevars(),
        nested(),
        lost(),
        cssnext(),
    ];
    return gulp.src([
            './src/css/*.css',
            './bower_components/openSans/openSans.css',
            './bower_components/components-font-awesome/css/font-awesome.min.css',
            './bower_components/bootstrap/dist/css/bootstrap.min.css',
        ])
        .pipe(postcss(processors))
        .pipe(gulp.dest('./build/css'));
});

gulp.task('ts', ['ts-app', 'ts-electron']);

gulp.task('build', ['templates', 'resources', 'styles', 'ts', 'libs', 'modules', 'images', 'javascript']);

gulp.task('watch', ['build'], () => {
    gulp.watch('./src/app/**/*', ['ts-app']);
    gulp.watch('./src/electron/**/*', ['ts-electron']);
    gulp.watch('./src/resources/**/*', ['resources']);
    gulp.watch('./src/css/**/*', ['styles']);
    gulp.watch('./src/templates/**/*', ['templates']);
    gulp.watch('./src/img/**/*', ['images']);
    gulp.watch('./src/js/**/*', ['javascript']);
});

平台：Win7x64 NPM：3.10.8 NODE：v6.7.0 Gulp版本：

{
    "gulp": "^3.9.1",
    "gulp-if": "^2.0.1",
    "gulp-postcss": "^6.1.1",
    "gulp-pug": "^3.0.3",
    "gulp-typescript": "^2.13.6",
    "gulp-uglify": "^1.5.4",
}

我还尝试手动放置gulp.dest("./build/", {overwrite: true})（在所有gulp.dest中），但没有任何改变：/ 我该怎么做才能更好地理解这个问题？