drush_make fails silently if it can't move the built drupal in place

This is a very peculiar issue.. As drush_make builds its stuff in the temporary directory and only moves it into place in the end, things seem all right from a user perspective:

sh-3.2$ /var/hostmaster/drush/drush.php  --root='/var/hostmaster/hostmaster-HEAD' make '/var/hostmaster/.drush/provision/aegir.make' '/var/hostmaster/hostmaster-0.4-alpha8+services' 
Project information for drupal retrieved.                                                                                                                                                                                           [ok]
drupal downloaded from http://ftp.drupal.org/files/projects/drupal-6.17.tar.gz.                                                                                                                                                     [ok]
hostmaster cloned from git://git.aegirproject.org/hostmaster.git.                                                                                                                                                                   [ok]
Found makefile: hostmaster.make                                                                                                                                                                                                     [ok]
Project information for admin_menu retrieved.                                                                                                                                                                                       [ok]
Project information for install_profile_api retrieved.                                                                                                                                                                              [ok]
Project information for jquery_ui retrieved.                                                                                                                                                                                        [ok]
Project information for modalframe retrieved.                                                                                                                                                                                       [ok]
admin_menu downloaded from http://ftp.drupal.org/files/projects/admin_menu-6.x-1.5.tar.gz.                                                                                                                                          [ok]
install_profile_api downloaded from http://ftp.drupal.org/files/projects/install_profile_api-6.x-2.1.tar.gz.                                                                                                                        [ok]
jquery_ui downloaded from http://ftp.drupal.org/files/projects/jquery_ui-6.x-1.3.tar.gz.                                                                                                                                            [ok]
modalframe downloaded from http://ftp.drupal.org/files/projects/modalframe-6.x-1.6.tar.gz.                                                                                                                                          [ok]
jquery_ui downloaded from http://jquery-ui.googlecode.com/files/jquery.ui-1.6.zip.                                                                                                                                                  [ok]

Everything looks fine, right? Wrong! The directory is simply absent!

Things become clearer on debug:

Executing: mv '/tmp/drush_make_tmp_1276710563'/'jquery.ui-1.6' '/tmp/drush_make_tmp_1276710563/__build__/profiles/hostmaster/modules/jquery_ui'/'jquery.ui' [10.75 sec, 6.37 MB]                                                       [notice]
Executing: mv '/tmp/drush_make_tmp_1276710563'/__build__ '/var/hostmaster/hostmaster-0.4-alpha8+services' [10.77 sec, 6.37 MB]                                                                                                         [notice]
  mv: ne peut déplacer `/tmp/drush_make_tmp_1276710563/__build__' vers `/var/hostmaster/hostmaster-0.4-alpha8+services': Permission non accordée
Executing: rm -r '/tmp/drush_make_tmp_1276710563' [10.79 sec, 6.37 MB]                                                                                                                                                                 [notice]
Command dispatch complete [10.91 sec, 6.33 MB]                                                                                                                                                                                         [notice]
Peak memory usage was 6.75 MB [10.92 sec, 6.33 MB]                                                                                                                                                                                     [memory]

That error message is in french (sorry) but it basically says mv can't move the directory in place.

This is probably a simple fix, i'll look if i can issue a patch.