fixes RVM aliasing [closes rails#62]

Fuzzy aliasing no longer worked here, being more strict.

Author: fxn

puppet/manifests/default.pp

@@ -2,6 +2,10 @@
 $as_vagrant   = 'sudo -u vagrant -H bash -l -c'
 $home         = '/home/vagrant'
 
+# Pick one modern enough, supported in recent Rails versions, and for which RVM
+# provides binaries.
+$ruby_version = '2.0.0-p353'
+
 Exec {
   path => ['/usr/sbin', '/usr/bin', '/sbin', '/bin']
 }
@@ -135,7 +139,7 @@
   # The rvm executable is more suitable for automated installs.
   #
   # use a ruby patch level known to have a binary
-  command => "${as_vagrant} '${home}/.rvm/bin/rvm install ruby-2.0.0-p353 --binary --autolibs=enabled && rvm alias create default 2.0'",
+  command => "${as_vagrant} '${home}/.rvm/bin/rvm install ruby-${ruby_version} --binary --autolibs=enabled && rvm alias create default ${ruby_version}'",
   creates => "${home}/.rvm/bin/ruby",
   require => Exec['install_rvm']
 }