Properly accumulate and parse cURL output for progress

lib/vagrant/util/downloader.rb

@@ -42,15 +42,26 @@ module Vagrant
           # tell us output so we can parse it out.
           options << { :notify => :stderr }
 
+          progress_data = ""
+          progress_regexp = /(\r(.+?))\r/
+
           # Setup the proc that'll receive the real-time data from
           # the downloader.
           data_proc = Proc.new do |type, data|
             # Type will always be "stderr" because that is the only
             # type of data we're subscribed for notifications.
 
-            # If the data doesn't start with a \r then it isn't a progress
-            # notification, so ignore it.
-            next if data[0] != "\r"
+            # Accumulate progress_data
+            progress_data << data
+
+            while true
+              # If we have a full amount of column data (two "\r") then
+              # we report new progress reports. Otherwise, just keep
+              # accumulating.
+              match = progress_regexp.match(progress_data)
+              break if !match
+              data = match[2]
+              progress_data.gsub!(match[1], "")
 
               # Ignore the first \r and split by whitespace to grab the columns
               columns = data[1..-1].split(/\s+/)
@@ -76,6 +87,7 @@ module Vagrant
               @ui.info(output, :new_line => false)
             end
           end
+        end
 
         # Create the callback that is called if we are interrupted
         interrupted  = false