Merge branch 'bc/more-git-var'

Fix-up for a topic that already has graduated.

* bc/more-git-var:
  var: avoid a segmentation fault when `HOME` is unset

Author: gitster

builtin/var.c

@@ -66,7 +66,7 @@ static char *git_attr_val_system(int ident_flag UNUSED)
 
 static char *git_attr_val_global(int ident_flag UNUSED)
 {
-	char *file = xstrdup(git_attr_global_file());
+	char *file = xstrdup_or_null(git_attr_global_file());
 	if (file) {
 		normalize_path_copy(file, file);
 		return file;

t/t0007-git-var.sh

@@ -268,4 +268,13 @@ test_expect_success 'listing and asking for variables are exclusive' '
 	test_must_fail git var -l GIT_COMMITTER_IDENT
 '
 
+test_expect_success '`git var -l` works even without HOME' '
+	(
+		XDG_CONFIG_HOME= &&
+		export XDG_CONFIG_HOME &&
+		unset HOME &&
+		git var -l
+	)
+'
+
 test_done