Vagrant: La sortie de progression du téléchargement rvm est corrompue

Je travaille sur le provisionnement via un script shell bash, et une étape provoque un comportement de sortie étrange.

Plus précisément l'étape d'installation de RVM :

sudo -u vagrant -H sh -c "\curl -sSL https://get.rvm.io | bash -s stable --rails"

Cela génère la sortie suivante - initialement casher, mais pendant la phase qui afficherait normalement une barre de progression, à la place, chaque caractère a principalement sa propre ligne, comme si les lettres étaient diffusées en tant qu'actions d'impression individuelles.

==> default: Downloading https://github.com/wayneeseguin/rvm/archive/stable.tar.gz
==> default: Installing RVM to /home/vagrant/.rvm/
==> default:     Adding rvm PATH line to /home/vagrant/.profile /home/vagrant/.bashrc /home/vagrant/.zshrc.
==> default:     Adding rvm loading line to /home/vagrant/.bash_profile /home/vagrant/.zlogin.
==> default: Installation of RVM in /home/vagrant/.rvm/ is almost complete:
==> default:   * To start using RVM you need to run `source /home/vagrant/.rvm/scripts/rvm`
==> default:     in all your open shell windows, in rare cases you need to reopen all shell windows.
==> default: # Administrator,
==> default: #
==> default: #   Thank you for using RVM!
==> default: #   We sincerely hope that RVM helps to make your life easier and more enjoyable!!!
==> default: #
==> default: # ~Wayne, Michal & team.
==> default: In case of problems: http://rvm.io/help and https://twitter.com/rvm_io
==> default: rvm 1.25.27 (stable) by Wayne E. Seguin <[email protected]>, Michal Papis <[email protected]> [https://rvm.io/]
==> default: Searching for binary rubies, this might take some time.
==> default: No binary rubies available for: ubuntu/14.04/i386/ruby-2.1.2.
==> default: Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
==> default: Checking requirements for ubuntu.
==> default: Requirements installation successful.
==> default: Installing Ruby from source to: /home/vagrant/.rvm/rubies/ruby-2.1.2, this may take a while depending on your cpu(s)...
==> default: ruby-2.1.2 - #downloading ruby-2.1.2, this may take a while depending on your connection...
==> default:  
==> default:  
==> default: %
==> default:  
==> default: T
==> default: o
==> default: t
==> default: a
==> default: l
==> default:  
==> default:  
==> default:  
==> default:  
==> default: %
==> default:  
==> default: R
==> default: e
==> default: c
==> default: e
==> default: i
==> default: v
==> default: e
==> default: d % Xferd  Average Speed   Time    Time     Time  Current
==> default:                                  Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
==> default:  
==> default:  
==> default: 0
==> default:  
==> default:  
==> default:  
==> default:  
==> default:  
==> default: 0
==> default:  
==> default:    0     0    0     0      0      0 --:--:--  0:00:01 --:--:--     0
  0     0    0     0    0     0      0      0 --:--:--  0:00:02 --:--:--     0
  0     0    0     0    0     0      0      0 --:--:--  0:00:03 --:--:--     0
  0     0    0     0    0     0      0      0 --:--:--  0:00:04 --:--:--     0
==> default:  
==> default:  
==> default: 0
==> default:  
==> default:  
==> default:  
==> default:  
==> default:  
==> default: 0
==> default:  
==> default:  
==> default:  
==> default:  
==> default: 0
==> default:  
==> default:  
  0     0    0     0    0     0      0      0 --:--:--  0:00:05 --:--:--     0
==> default:  
==> default:  
==> default: 8
==> default:  
==> default: 1
==> default: 1
==> default: .
==> default: 4
==> default: M
==> default:  
==> default:  
==> default:  
==> default:  
==> default: 8
==> default:  
==> default:  
==> default: 9
==> default: 6
==> default: 1
==> default: k
==> default:  
==> default:  
==> default:  
==> default:  
==> default: 0
==> default:  
==> default:     0   146k      0  0:01:20  0:00:06  0:01:14  237k
==> default:  
==> default: 31 11.4M   31 3694k    0     0   488k      0  0:00:23  0:00:07  0:00:16  916k
==> default:  
==> default: 8
==> default: 3
==> default:  
==> default: 1
==> default: 1
==> default: .
==> default: 4
==> default: M
==> default:  
==> default:  
==> default:  
==> default: 8
==> default: 3
==> default:  
==> default: 9
==> default: 7
==> default: 6
==> default: 1
==> default: k
==> default:  
==> default:    0     0  1141k      0  0:00:10  0:00:08  0:00:02 2429k
==> default: 1
==> default: 0
==> default: 0
==> default:  
==> default: 1
==> default: 1
==> default: .
==> default: 4
==> default: M
==> default:   100 11.4M    0     0  1325k      0  0:00:08  0:00:08 --:--:-- 3558k
==> default: ruby-2.1.2 - #extracting ruby-2.1.2 to /home/vagrant/.rvm/src/ruby-2.1.2
==> default: ...
==> default: ruby-2.1.2 - #configuring

Cela semble peut-être lié à https://github.com/mitchellh/vagrant/issues/471 , bien que ce problème se manifeste différemment (duplication de lignes plutôt que segmentation de caractères).

Environnement:
Vagabond 1.6.2
Linux Mint 16 (Pétra)