`eval` of a string starting with a blank line raises `SyntaxError`

The following succeeds with CPython:

```python
# should not throw
eval(" 3.14")  # OK
eval("\t3.14") # OK
eval("\n3.14") # raises SyntaxError in ipy

# should raise SyntaxError
try: eval("\n 3.14")
except SyntaxError: pass  # OK
else: assert False
```
