df.to_feather pandas:  Failed to open local file, error: The requested operation cannot be performed on a file with a user-mapped section open.
#### Code Sample, a copy-pastable example if possible

```python
# Your code here
df = pd.DataFrame({'Loan':["L1","L2"], 'Gender':["male","Female"], "income":[25000.324, 43422.2754]})
df

df['income'] = df['income'].round(decimals=2)
df = df.astype(dict(zip(['Gender'], ['category'])), copy = True)
df

df.to_feather("temp")
df = pd.read_feather("temp")
df.to_feather("temp")
```
#### Problem description
I applied round function on a column and then applied object to category conversion.
I saved the final dataframe into feather file.

When i tried to read the feather file and save the feather file again, I'm getting file is open as per the error. Now able to understand, why the file is getting locked when i read the feather file. Any help on this is appreciated

Using pandas 1.0.0 and python 3.6.5v