RecursionError with self referencing column in str(df) on DataFrame
```python
# Your code here
b = a = pd.Series(
    [2, 1, 3],
    index=[2, 1, 3],
)
# display(b)
a['Hi'] = b
print(str(a))
```

This raises
```python
RecursionError: maximum recursion depth exceeded in __instancecheck__
```

It is annoying when this happens in interactive mode.

#### Expected Output

```
2                                     2
1                                     1
3                                     3
Hi    2    2
1    1
3    3
dtype: int64
dtype: object
```

#### Output of ``pd.show_versions()``

<details>

```
INSTALLED VERSIONS
------------------
commit: None
python: 3.7.2.final.0
python-bits: 64
OS: Windows
OS-release: 10
machine: AMD64
processor: Intel64 Family 6 Model 158 Stepping 9, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None
LOCALE: None.None

pandas: 0.24.1
pytest: None
pip: 18.1
setuptools: 40.6.3
Cython: 0.29.4
numpy: 1.16.1
scipy: 1.2.0
pyarrow: None
xarray: None
IPython: 7.2.0
sphinx: None
patsy: 0.5.1
dateutil: 2.7.5
pytz: 2018.9
blosc: None
bottleneck: None
tables: None
numexpr: None
feather: None
matplotlib: None
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml.etree: None
bs4: None
html5lib: None
sqlalchemy: 1.2.18
pymysql: None
psycopg2: None
jinja2: 2.10
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None
gcsfs: None
```

</details>
