careful, ARGV items are frozen

lib/hub/commands.rb

@@ -374,11 +374,11 @@ module Hub
         idx = args.index(url)
         gist = $1 == 'gist.'
         # strip the fragment part of the url
-        url.sub!(/#.+/, '')
+        url = url.sub(/#.+/, '')
         # strip extra path from "pull/42/files", "pull/42/commits"
-        url.sub!(%r{(/pull/\d+)/\w*$}, '\1') unless gist
+        url = url.sub(%r{(/pull/\d+)/\w*$}, '\1') unless gist
         ext = gist ? '.txt' : '.patch'
-        url << ext unless File.extname(url) == ext
+        url += ext unless File.extname(url) == ext
         patch_file = File.join(ENV['TMPDIR'] || '/tmp', "#{gist ? 'gist-' : ''}#{File.basename(url)}")
         args.before 'curl', ['-#LA', "hub #{Hub::Version}", url, '-o', patch_file]
         args[idx] = patch_file

test/helper.rb

@@ -16,7 +16,7 @@ class Test::Unit::TestCase
   # shell: hub clone rtomayko/tilt
   #  test: Hub("clone rtomayko/tilt")
   def Hub(args)
-    Hub::Runner.new(*args.split(' '))
+    Hub::Runner.new(*args.split(' ').map {|a| a.freeze })
   end
 
   # Shortcut for running the `hub` command in a subprocess. Returns