1.7.2 bug

With
```python
def f():
    """CC.

    :math:`f(0) = 1`. XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXX
    """
```

which produces inserts a blank space after the second `:`
```python
def f():
    """CC.

    :math: `f(0) = 1`. XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
        XXXXXXXXXXXXXXXXXXXXXX
    """
```