Box add URL with windows drive letter works properly

CHANGELOG.md

@@ -22,6 +22,8 @@ BUG FIXES:
     fail to detect the box. [GH-1617]
   - In a multi-machine environment, a box not found won't be downloaded
     multiple times. [GH-1467]
+  - `vagrant box add` with a file path now works correctly on Windows
+    when a drive letter is specified.
 
 ## 1.2.1 (April 17, 2013)
 

lib/vagrant/action/builtin/box_add.rb

@@ -19,8 +19,8 @@ module Vagrant
           @logger.info("Downloading box to: #{@temp_path}")
 
           url = env[:box_url]
-          if url !~ /^[a-z0-9]+:.*$/i
-            @logger.info("No protocol found on box URL, assuming file:")
+          if File.file?(url) || url !~ /^[a-z0-9]+:.*$/i
+            @logger.info("URL is a file or protocol not found and assuming file.")
             file_path = File.expand_path(url)
             file_path = Util::Platform.cygwin_windows_path(file_path)
             url = "file:#{file_path}"