t1900: avoid using -C <dir> for a bare repository

To prepare for `safe.bareRepository` defaulting to `explicit` (see
8d1a744), add an optional 6th parameter `repo_flag` (defaulting
to `-C`) to the `test_repo_info` helper, and use it in the caller that
wants to operate on a bare repository.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

t/t1900-repo-info.sh

@@ -20,20 +20,21 @@ test_repo_info () {
 	repo_name=$3
 	key=$4
 	expected_value=$5
+	repo_flag=${6:--C}
 
 	test_expect_success "setup: $label" '
 		eval "$init_command $repo_name"
 	'
 
 	test_expect_success "lines: $label" '
 		echo "$key=$expected_value" > expect &&
-		git -C "$repo_name" repo info "$key" >actual &&
+		git $repo_flag "$repo_name" repo info "$key" >actual &&
 		test_cmp expect actual
 	'
 
 	test_expect_success "nul: $label" '
 		printf "%s\n%s\0" "$key" "$expected_value" >expect &&
-		git -C "$repo_name" repo info --format=nul "$key" >actual &&
+		git $repo_flag "$repo_name" repo info --format=nul "$key" >actual &&
 		test_cmp_bin expect actual
 	'
 }
@@ -48,7 +49,7 @@ test_repo_info 'bare repository = false is retrieved correctly' \
 	'git init' 'nonbare' 'layout.bare' 'false'
 
 test_repo_info 'bare repository = true is retrieved correctly' \
-	'git init --bare' 'bare' 'layout.bare' 'true'
+	'git init --bare' 'bare' 'layout.bare' 'true' '--git-dir'
 
 test_repo_info 'shallow repository = false is retrieved correctly' \
 	'git init' 'nonshallow' 'layout.shallow' 'false'