Last file missing from extracted tarball after config full export

Problem/Motivation

When exporting configuration from /admin/config/development/configuration/full/export, the last file is missing from the tarball config.tar.gz, for example views.view.who_s_online.yml. It is not missing when the export is done using drush cex

How to recreate the issue:

step 1:
Fresh install of the latest Drupal version 8.0.x-dev.

Export and import archive via UI without extracting

step 2: Make sure staging directory is empty.
step 3: Grab export archive from /admin/config/development/configuration/full/export and save it somewhere.
step 4: Go to /admin/config/development/configuration/full/import and import archive
step 5: Check staging directory, notice views.view.who_s_online.yml is there!
step 6: Extract the archive somewhere (not in staging, you just wanna see the contents), look for views.view.who_s_online.yml. Result: it's not there!

Reproduce issue by modifying ConfigController.php

step 2:
Open core/modules/config/src/controller/ConfigController.php and modify the downloadExport function as follows:

    $file_list = array(); // added this line for debugging purpose
    foreach ($this->configManager->getConfigFactory()->listAll() as $name) {
      $archiver->addString("$name.yml", Yaml::encode($this->configManager->getConfigFactory()->get($name)->getRawData()));
      $file_list[] = "$name.yml"; // added this line for debugging purpose
    }

step 3:
Do a full config export and compare the content of $file_list and your config.tar.gz file. The last file of $file_list is missing from tarball.

Reproduce issue using Drush

step 2: Preferably version control the staging directory so you can see changes better. Use drush cex to dump your config into staging directory. Check files, notice views.view.who_s_online.yml
step 3 :Delete all files from staging directory. Go to /admin/config/development/configuration/full/export, grab the archive, extract it to staging. Check files, notice that views.view.who_s_online.yml is there.

laszlo.kovacs devel config:
ubuntu 14.04
PHP Version 5.5.9-1ubuntu4.6

aschiwi devel config:
OS X Yosemite 10.0
PHP Version 5.4.34