BUG: undo_patch should only reset to non None values
The following snippet now runs as expected:
```python
from daal4py.sklearn.monkeypatch import dispatcher
dispatcher.disable()
from sklearn.cluster import KMeans
kmeans = KMeans(n_clusters=20, random_state=42, algorithm="full", \
max_iter=1000)
```
Previously, it would erroneously set `sklearn.cluster.KMeans` class
to `None`.
@@ -65,6 +65,7 @@ def do_unpatch(name):
lname = name.lower()
if lname in _mapping:
for descriptor in _mapping[lname]:
+ if descriptor[1] is not None:
which, what, replacer = descriptor[0]
setattr(which, what, descriptor[1])
else:
