Do not remove blank strings on strip, closes elixir-lang#282

THe previous behavior was wrong, the current behavior
matches Ruby and Perl.

lib/regex.ex

@@ -183,9 +183,7 @@ defmodule Regex do
   """
   def split({ Regex, compiled, _, _ }, string, parts // :infinity) do
     options = [{ :return, return_for(string) }, :trim, { :parts, parts }]
-    list  = Erlang.re.split(string, compiled, options)
-    blank = blank_for(string)
-    lc l in list when l != blank, do: l
+    Erlang.re.split(string, compiled, options)
   end
 
   @doc %B"""
@@ -230,9 +228,6 @@ defmodule Regex do
 
   # Private Helpers
 
-  defp blank_for(element) when is_binary(element), do: ""
-  defp blank_for(element) when is_list(element),   do: ''
-
   defp return_for(element) when is_binary(element), do: :binary
   defp return_for(element) when is_list(element),   do: :list
 

test/elixir/regex_test.exs

@@ -49,6 +49,9 @@ defmodule Regex.BinaryTest do
     assert Regex.split(%r" ", "foo bar baz") == ["foo", "bar", "baz"]
     assert Regex.split(%r" ", "foo bar baz", 2) == ["foo", "bar baz"]
     assert Regex.split(%r"\s", "foobar") == ["foobar"]
+    assert Regex.split(%r" ", "foo bar baz") == ["foo", "bar", "baz"]
+    assert Regex.split(%r"=", "key=") == ["key", ""]
+    assert Regex.split(%r"=", "=value") == ["", "value"]
   end
 
   test :replace do