[BUG] Dataframe.rank() produces wrong results for float columns
#### Code to reproduce the issue

```python
import numpy as np
import pandas as pd

indx = np.array([5, 4, 3, 2, 1, 6, 7, 8, 9, 10])
col1 = np.array([5, 4, 3, 5, 8, 5, 2, 1, 6, 6])
col2 = np.array([5, 4, np.nan, 5, 8, 5, np.inf, np.nan, 6, -np.inf])
pdf = pd.DataFrame(index=indx)
pdf["col1"] = col1.astype('f8')
pdf["col2"] = col2.astype('f8')

ranked_df = pdf.rank()

ranked_series = pd.DataFrame(index=indx)
ranked_series["col1"] = pdf["col1"].rank()
ranked_series["col2"] = pdf["col2"].rank()

print(ranked_df.equals(ranked_series))
#False
```
#### Problem description

Dataframe rank produces individual column ranks. But when float column is present, individual ranks are not equal to Dataframe rank. 

#### Expected Output
`True`

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

<details>

pd.show_versions()                                                                                                  

INSTALLED VERSIONS
------------------
commit           : None
python           : 3.8.1.final.0
python-bits      : 64
OS               : Linux
OS-release       : 4.15.0-72-generic
machine          : x86_64
processor        : x86_64
byteorder        : little
LC_ALL           : None
LANG             : en_US.UTF-8
LOCALE           : en_US.UTF-8

pandas           : 1.0.1
numpy            : 1.18.1
pytz             : 2019.3
dateutil         : 2.8.1
pip              : 20.0.2
setuptools       : 46.0.0.post20200309
Cython           : None
pytest           : None
hypothesis       : None
sphinx           : None
blosc            : None
feather          : None
xlsxwriter       : None
lxml.etree       : None
html5lib         : None
pymysql          : None
psycopg2         : None
jinja2           : None
IPython          : 7.12.0
pandas_datareader: None
bs4              : None
bottleneck       : None
fastparquet      : None
gcsfs            : None
lxml.etree       : None
matplotlib       : None
numexpr          : None
odfpy            : None
openpyxl         : None
pandas_gbq       : None
pyarrow          : None
pytables         : None
pytest           : None
pyxlsb           : None
s3fs             : None
scipy            : None
sqlalchemy       : None
tables           : None
tabulate         : None
xarray           : None
xlrd             : None
xlwt             : None
xlsxwriter       : None
numba            : None
</details>
