elixir-lang/elixir — pull request #2039 by pragdave (2014-02-07 02:30:46+00:00)
Title: print_doc_arg attempted to handle arguments with defaults. 

However, it added " \\ " between them, which is actually the string " \ ". This meant that (for example)

h IO.puts

displayed

def puts(device \ group_leader(), item)

Changed `print_doc_arg` to escape both backslashes.