TypeError: b2a_base64() argument 1 must be convertible to a buffer, not ConnectorSession

```
Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/wdb/ui.py", line 193, in loop
stop = self.interact()
File "/usr/local/lib/python2.7/dist-packages/wdb/ui.py", line 240, in interact
rv = fun(data)
File "/usr/local/lib/python2.7/dist-packages/wdb/ui.py", line 774, in do_display
'val': from_bytes(b64encode(thing)),
File "/usr/lib/python2.7/base64.py", line 54, in b64encode
encoded = binascii.b2a_base64(s)[:-1]
TypeError: b2a_base64() argument 1 must be convertible to a buffer, not ConnectorSession

```

Start in wdb/ui.py at do_display around line 774, where ConnectorSession is passed to b64encode and the traceback occurs. Trace how displayed values reach this entry point, then verify that ConnectorSession values no longer raise the TypeError and add or run a regression check if the project provides one.

Written by the indexing model from the issue text.