Fix String.replace_leading/3 bug when the rest of string equals match

Author: lexmag

lib/elixir/lib/string.ex

@@ -628,7 +628,7 @@ defmodule String do
     replace_leading(string, match, replacement, prefix_size, suffix_size, "")
   end
 
-  defp replace_leading(string, match, replacement, prefix_size, suffix_size, acc) when suffix_size > 0 do
+  defp replace_leading(string, match, replacement, prefix_size, suffix_size, acc) when suffix_size >= 0 do
     case string do
       <<prefix::size(prefix_size)-binary, suffix::size(suffix_size)-binary>> when prefix == match ->
         replace_leading(suffix, match, replacement, prefix_size, suffix_size - prefix_size, acc <> replacement)