Gulp 4: Watch task is executed per each matched file during startup

Created by: demisx

My versions:

gulp -v
[21:59:43] CLI version 0.4.0
[21:59:43] Local version 4.0.0-alpha.1

I have a watch task to run unit tests defined like this:

gulp.task('unit', function () {
  // piping files to gulp-mocha here
  ...
});

gulp.task('watch:unit', function () {
  gulp.watch(['app/**/*.js', '!app/**/*.spec.js'], gulp.parallel('unit'));
});

The strange behavior I'm seeing now is that when I run the gulp watch:unit task first time it tries to run the unit task for each matched *.js file (see the output below). I don't recall having this issue before.

$ gulp watch:unit
[22:02:20] Using gulpfile ~/projects/web-services/data-api/gulpfile.js
[22:02:20] Starting 'watch:unit'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'unit'...

  0 passing (1ms)
  ․
  ․․․[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'parallel'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'unit'...
[22:02:20] Starting 'unit'...
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
  0 passing (0ms)
․․․․․․․․․․
  7 passing (156ms)
  7 passing (125ms)