Set evaluation to empty space to fix string replace on batch, closes elixir-lang#10495 (elixir-lang#10586)

Author: josevalim

bin/elixir.bat

@@ -99,18 +99,21 @@ if !par!=="+elixirc" (set parsElixir=!parsElixir! +elixirc && set runMode="elixi
 rem ******* EVAL PARAMETERS ************************
 if ""==!par:-e=! (
   set "VAR=%~1"
+  if not defined VAR (set VAR= )
   set parsElixir=!parsElixir! -e "!VAR:"=\"!"
   shift
   goto startloop
 )
 if ""==!par:--eval=! (
   set "VAR=%~1"
+  if not defined VAR (set VAR= )
   set parsElixir=!parsElixir! --eval "!VAR:"=\"!"
   shift
   goto startloop
 )
 if ""==!par:--rpc-eval=! (
   set "VAR=%~2"
+  if not defined VAR (set VAR= )
   set parsElixir=!parsElixir! --rpc-eval %1 "!VAR:"=\"!"
   shift
   shift

lib/elixir/test/elixir/kernel/cli_test.exs

@@ -23,6 +23,11 @@ defmodule Kernel.CLITest do
              assert run(["-e", "IO.puts :ok", "--", "sample.exs", "-o", "1", "2"]) ==
                       ["sample.exs", "-o", "1", "2"]
            end) == "ok\n"
+
+    assert capture_io(fn ->
+             assert run(["-e", "", "--", "sample.exs", "-o", "1", "2"]) ==
+                      ["sample.exs", "-o", "1", "2"]
+           end)
   end
 
   test "properly parses paths" do