Slightly more robust extension downloader.

examples/ninesixty/bootstrap.rb

@@ -20,12 +20,14 @@ end
 
 
 if !File.exists?(extdir)
-  puts "Downloading and unpacking the ninesixty plugin."
+  begin
+    puts "Downloading the ninesixty plugin."
     FileUtils.mkdir(extdir)
     zipfile = File.join(extdir, "ninesixty.zip")
     open(zipfile, "wb") do |tgz|
       tgz << fetch(download_link).body
     end
+    puts "Unzipping the ninesixty plugin."
     Zip::ZipFile::open(zipfile) { |zf|
        zf.each { |e|
          fpath = File.join(extdir, e.name)
@@ -36,4 +38,8 @@ if !File.exists?(extdir)
     File.unlink(zipfile)
     funky_directory = Dir.glob(File.join(extdir,'chriseppstein-compass-960-plugin-*'))[0]
     FileUtils.mv(funky_directory, File.join(extdir,'ninesixty'))
+  rescue Exception => e
+    FileUtils.rmdir(extdir)
+    raise
+  end
 end