I don't think this really addresses the issue properly...

The original docstring read:
+Note that not specifying sep (or using None) will cause\n\
+empty strings to be removed from the output. thus ' '.strip()\n\
+returns []. while ' '.strip(' ') returns ['', ''].
(Obviously strip is wrong here, it should be split)

The committed docstring reads:
+If sep is not specified or is None, any whitespace string is a
separator and leading and trailing whitespace is stripped before splitting.

But the point is not just that leading and trailing whitespace is
stripped; ''.strip() returns [] while ''.strip(' ') returns ['']. This
is probably the most unexpected corner case; it seems to be better to
say that empty strings are removed from the output.