Merge branch 'sg/complete-configuration-variables'

Command line completion updates for "git -c var.name=val" * sg/complete-configuration-variables: completion: complete config variables and values for 'git clone --config=' completion: complete config variables names and values for 'git clone -c' completion: complete values of configuration variables after 'git -c var=' completion: complete configuration sections and variable names for 'git -c' completion: split _git_config() completion: simplify inner 'case' pattern in __gitcomp() completion: use 'sort -u' to deduplicate config variable names completion: deduplicate configuration sections completion: add tests for 'git config' completion completion: complete more values of more 'color.*' configuration variables completion: fix a typo in a comment