t7004-tag: use test_config helper

... instead of setting and then manually unsetting configuration
variables, on one occasion even outside the test_expect_success block.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7004-tag.sh

@@ -297,11 +297,9 @@ EOF
 '
 
 test_expect_success 'listing tags in column with column.*' '
-	git config column.tag row &&
+	test_config column.tag row &&
-	git config column.ui dense &&
+	test_config column.ui dense &&
 	COLUMNS=40 git tag -l >actual &&
-	git config --unset column.ui &&
-	git config --unset column.tag &&
 	cat >expected <<\EOF &&
 a1      aa1   cba     t210    t211
 v0.2.1  v1.0  v1.0.1  v1.1.3
@@ -314,9 +312,8 @@ test_expect_success 'listing tag with -n --column should fail' '
 '
 
 test_expect_success 'listing tags -n in column with column.ui ignored' '
-	git config column.ui "row dense" &&
+	test_config column.ui "row dense" &&
 	COLUMNS=40 git tag -l -n >actual &&
-	git config --unset column.ui &&
 	cat >expected <<\EOF &&
 a1              Foo
 aa1             Foo
@@ -1200,11 +1197,10 @@ test_expect_success GPG,RFC1991 \
 '
 
 # try to sign with bad user.signingkey
-git config user.signingkey BobTheMouse
 test_expect_success GPG \
 	'git tag -s fails if gpg is misconfigured (bad key)' \
-	'test_must_fail git tag -s -m tail tag-gpg-failure'
+	'test_config user.signingkey BobTheMouse &&
-git config --unset user.signingkey
+	test_must_fail git tag -s -m tail tag-gpg-failure'
 
 # try to produce invalid signature
 test_expect_success GPG \
@@ -1484,7 +1480,7 @@ test_expect_success 'reverse lexical sort' '
 '
 
 test_expect_success 'configured lexical sort' '
-	git config tag.sort "v:refname" &&
+	test_config tag.sort "v:refname" &&
 	git tag -l "foo*" >actual &&
 	cat >expect <<-\EOF &&
 	foo1.3
@@ -1495,6 +1491,7 @@ test_expect_success 'configured lexical sort' '
 '
 
 test_expect_success 'option override configured sort' '
+	test_config tag.sort "v:refname" &&
 	git tag -l --sort=-refname "foo*" >actual &&
 	cat >expect <<-\EOF &&
 	foo1.6
@@ -1509,13 +1506,12 @@ test_expect_success 'invalid sort parameter on command line' '
 '
 
 test_expect_success 'invalid sort parameter in configuratoin' '
-	git config tag.sort "v:notvalid" &&
+	test_config tag.sort "v:notvalid" &&
 	test_must_fail git tag -l "foo*"
 '
 
 test_expect_success 'version sort with prerelease reordering' '
-	git config --unset tag.sort &&
+	test_config versionsort.prereleaseSuffix -rc &&
-	git config versionsort.prereleaseSuffix -rc &&
 	git tag foo1.6-rc1 &&
 	git tag foo1.6-rc2 &&
 	git tag -l --sort=version:refname "foo*" >actual &&
@@ -1530,6 +1526,7 @@ test_expect_success 'version sort with prerelease reordering' '
 '
 
 test_expect_success 'reverse version sort with prerelease reordering' '
+	test_config versionsort.prereleaseSuffix -rc &&
 	git tag -l --sort=-version:refname "foo*" >actual &&
 	cat >expect <<-\EOF &&
 	foo1.10