!ls fails

!ls works the first time it is run. The second time there is no output. Also, it appears that !cd does not work. If I !cd to a directory and then !ls, I get a listing of the parent directory.

Reproduce the issue in a Carnets notebook by running !ls twice, then use !cd followed by !ls. Trace the notebook shell-command execution path and verify that repeated commands produce output and that changing directories affects the following listing.

Written by the indexing model from the issue text.