Revert "t6006: drop "always" color config tests"

This reverts commit c5bdfe677c.

That commit was done primarily to prepare for the weakening
of "always" in 6be4595edb (color: make "always" the same as
"auto" in config, 2017-10-03). But since we've now reverted
6be4595edb, there's no need for us to remove "-c
color.ui=always" from the tests. And in fact it's a good
idea to restore these tests, to make sure that "always"
continues to work.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t6006-rev-list-format.sh

@@ -208,11 +208,26 @@ do
 		has_no_color actual
 	'
 
+	test_expect_success "$desc enables colors for color.diff" '
+		git -c color.diff=always log --format=$color -1 >actual &&
+		has_color actual
+	'
+
+	test_expect_success "$desc enables colors for color.ui" '
+		git -c color.ui=always log --format=$color -1 >actual &&
+		has_color actual
+	'
+
 	test_expect_success "$desc respects --color" '
 		git log --format=$color -1 --color >actual &&
 		has_color actual
 	'
 
+	test_expect_success "$desc respects --no-color" '
+		git -c color.ui=always log --format=$color -1 --no-color >actual &&
+		has_no_color actual
+	'
+
 	test_expect_success TTY "$desc respects --color=auto (stdout is tty)" '
 		test_terminal git log --format=$color -1 --color=auto >actual &&
 		has_color actual
@@ -225,11 +240,6 @@ do
 			has_no_color actual
 		)
 	'
-
-	test_expect_success TTY "$desc respects --no-color" '
-		test_terminal git log --format=$color -1 --no-color >actual &&
-		has_no_color actual
-	'
 done
 
 test_expect_success '%C(always,...) enables color even without tty' '