The %paste magic can try a number of options, but on Linux it depends on having Tkinter installed. As reported on the mailing list, if Tkinter is missing, the user gets a traceback and an uninformative TryNext exception. We should catch this and provide a more informative message.
Note that this should also close #211, where it is detected as just not working, presumably on account of the lame error.
Fix issue #880 - initialize TryNext with args and kwargs.
Presents a message to the user along with the traceback prompting them to install tkinter.
Closed by PR #999, merged in 6c20358.