Incorrect completion of subcommands

[fmbenhassine]

While commands completion works, sub-commands completion seems to loose context about the previous input. In the petclinic sample, try the following:

Type vet + Tab + Tab (to select the list subcommand) + Enter:

shell:>vets\ list
vets info: Show details of a given veterinarian (show the details of a given veterinarian)
vets list: List veterinarians                              (Command to list veterinarians)

At this point, the prompt shows: shell:>vets\ list (the \ is incorrect, but will be fixed separately in #1228). Now if I type Tab again, I see all commands which is obviously incorrect:

shell:>vets\ list
Built-In Commands
clear: Clear the terminal screen                       (clear(): Clear the terminal screen)
help: Display help about available commands (help(): Display help about available commands)
script: Execute commands from a script file (script(): Execute commands from a script file)
version: Show version info                                   (version(): Show version info)
Owners
owners info: Show details of a given owner              (show the details of a given owner)
owners list: List owners                                           (Command to list owners)
Pets
pets info: Show detail about a given pet               (Show the details about a given pet)
pets list: List pets                                              (List pets in Pet Clinic)
Vets
vets info: Show details of a given veterinarian  (show the details of a given veterinarian)
vets list: List veterinarians

The completion should always show sub commands of the current selection if any, or stop (showing available options is nice to have, but this is out of scope here).