dojo: reset =dir during migration
The base desk is the new default. If we leave the dir untouched, for
most users this means they remain on home, which gets rendered
explicitly in the prompt since it's no longer the default desk.
++ session-6-to-7
|= old=session-6
~? ?=(^ poy.old) [dap.hid %cancelling-for-load]
- old(poy ~)
+ old(poy ~, -.dir [our.hid %base ud+0])
::
+$ house-5
[%5 egg=@u hoc=(map id session)]
