Merge branch 'jk/colors-fix' into maint

"git config --get-color" did not parse its command line arguments
carefully.

* jk/colors-fix:
t4026: test "normal" color
config: fix parsing of "git config --get-color some.key -1"
docs: describe ANSI 256-color mode

diff --cc Documentation/config.txt
Simple merge

diff --cc builtin/config.c
Simple merge