Merge branch 'bb/rgb-12-bit-colors'

The color parsing code learned to handle 12-bit RGB colors, spelled as "#RGB" (in addition to "#RRGGBB" that is already supported). * bb/rgb-12-bit-colors: color: add support for 12-bit RGB colors t/t4026-color: add test coverage for invalid RGB colors t/t4026-color: remove an extra double quote character