Made Mix.Utils.camelize handle empty string

Author: jwarwick

lib/mix/lib/mix/utils.ex

@@ -238,6 +238,8 @@ defmodule Mix.Utils do
       Mix.Utils.camelize "foo_bar" #=> "FooBar"
 
   """
+  def camelize(""), do: ""
+
   def camelize(<<?_, t :: binary>>) do
     camelize(t)
   end

lib/mix/test/mix/utils_test.exs

@@ -67,6 +67,7 @@ defmodule Mix.UtilsTest do
     assert Mix.Utils.camelize("_foo") == "Foo"
     assert Mix.Utils.camelize("foo__bar") == "FooBar"
     assert Mix.Utils.camelize("foo/bar") == "Foo.Bar"
+    assert Mix.Utils.camelize("") == ""
   end
 
   test :extract_files do