QST:bug or not? silent fail of df.iloc[].loc[] = newDataType
If I use a loc chained to a iloc I can change a value if it is of the same dtype:
```python
df = pd.DataFrame([[0, 2, 3], [0, 4, 1], [10, 20, 30]],
...                   index=[4, 5, 6], columns=['A', 'B', 'C'])
df.iloc[1].loc["B"] = 999
df
    A    B   C
4   0    2   3
5   0  999   1
6  10   20  30
```
This changes the value to 999.
However, this does not work and fails silently if the dtype is different:
```python
df.iloc[1].loc["B"] = "888"
df
    A    B   C
4   0    2   3
5   0  999   1
6  10   20  30
```
The value is not changed and there is no error raised.
This seems not consistent with the behavior of doing this:
```python
df.iloc[1,1] = "888"
df
    A    B   C
4   0    2   3
5   0  888   1
6  10   20  30
```
the last code above changes the type of the column silently.
```
df.dtypes
A     int64
B    object
C     int64
```
Envirnt:
```
Python 3.8.5
pd.__version__ : '1.1.3'
```
I am only a beginner in pandas so I am wondering if this should be reported as a bug or requesting a feature request or if this behavior is normal. 
