The command line completion script (in contrib/) learned to
complete configuration variable names better.
* pb/complete-config:
completion: add and use __git_compute_second_level_config_vars_for_section
completion: add and use __git_compute_first_level_config_vars_for_section
completion: complete 'submodule.*' config variables
completion: add space after config variable names also in Bash 3
89400c3615