pyre2 anchor '$' have non standard non re compatible  behaviour

documentation of gnu regex and also re module says:

> This operator can match the empty string either at the end of the string or **before a newline character** in the string

look at this simple example:

```
re.findall(r'abc$', 'bla bla abc\n')
['abc']

re2.findall(r'abc$',  'bla bla abc\n')
[]
```

Is this behaviour is intentionally?
