Log Message:
Update misc/py-anita to 1.31.  Changes from 1.30:

Fix a failure to consume a shell prompt which would cause it to remain
buffered and later be mistaken for one that had not yet issued.  For
added protection, add a unique serial number to each prompt.

Omit drive index from qemu command line for backwards compatibility
with scripts written for anita 1.29 or older.

Fix X11 set names.