reproducing case:

file.py:

```
"""
Hello \n blah.
"""
```

And then in a REPL (2.7 or 3+):

```
>>> import ast
>>> f = ast.parse(open("test.py", 'rb').read())
>>> f
<_ast.Module object at 0x7f609d0a4d68>
>>> f.body[0]
<_ast.Expr object at 0x7f609d0a4e10>
>>> f.body[0].value
<_ast.Str object at 0x7f609d02b780>
>>> f.body[0].value.s
'\nHello \n blah.\n'
>>> repr(f.body[0].value.s)
"'\\nHello \\n blah.\\n'"
```

Expected behaviour:
```
>>> repr(f.body[0].value.s)
"'\\nHello \\\\n blah.\\n'"
```