Properly convert provider name to symbol when searching for boxes

[GH-1691]

CHANGELOG.md

@@ -25,6 +25,8 @@ BUG FIXES:
     carry on checks whether the halt succeeded. [GH-1679]
   - Handle the case where a roles path for Chef solo isn't properly
 	defined. [GH-1665]
+  - Finding V1 boxes now works properly again to avoid "box not found"
+    errors. [GH-1691]
 
 ## 1.2.2 (April 23, 2013)
 

lib/vagrant/box_collection.rb

@@ -234,7 +234,7 @@ module Vagrant
 
         # If we're looking for a VirtualBox box, then we check if there is
         # a V1 box.
-        if provider == :virtualbox
+        if provider.to_sym == :virtualbox
           # Check if a V1 version of this box exists, and if so, raise an
           # exception notifying the caller that the box exists but needs
           # to be upgraded. We don't do the upgrade here because it can be