check whether safeCPickleDumps(obj): is still needed

[sbillinge]

This may be another py2 compatibility function. Check where it is used and whether it can be removed.

Write tests to make sure the behavior is still handled.

[Tieqiong]

@sbillinge this method ensures that an object is serialized even if it contains problematic floating-point values by falling back to a simpler serialization protocol if the default one fails.

In Python 3, the pickle module uses more recent protocols, and the SystemError related to frexp() is less likely to occur. So I think the fallback to ASCII protocol (protocol 0) is not necessary any more.

Yes test would be the right thing to do