- Update to 2.9.4
* Fallback for failure to import numpy or pandas is now dissociated from
failure to import :mod:`numpy2ri` or :mod:`pandas2ri` (issue #463).
* :func:`repr` for R POSIX date/time vectors is now showing a string
representation of the date/time rather than the timestamp as a float
(issue #467).
* The HTML representation of R data frame (the default representation in the
Jupyter notebook) was displaying an inconsistent number of rows
(found while workin on issue #466).
* Handle time zones in timezones in Pandas when converting to R data frames
(issue #454).
* When exiting the Python process, the R cleanup is now explicitly request
to happen before Python's exit. This is preventing possible segfaults
the process is terminating (issue #471).
* dplyr method `ungroup()` was missing from
:class:`rpy2.robjects.lib.dplyr.DataFrame` (issue #473).