[ostree] tests: Fix root uid check in test-commit-sign.sh

[Matthew Barnes <mbarnes src gnome org>]

commit a1352fec9deb2f8aaaf2a61af0f5c83611962507
Author: Matthew Barnes <mbarnes redhat com>
Date:   Tue Apr 14 08:53:48 2015 -0400

    tests: Fix root uid check in test-commit-sign.sh

 tests/test-commit-sign.sh |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/tests/test-commit-sign.sh b/tests/test-commit-sign.sh
index 01a3a2e..0db0048 100755
--- a/tests/test-commit-sign.sh
+++ b/tests/test-commit-sign.sh
@@ -25,7 +25,7 @@ fi
 
 # Skip the test when non-root as gpgme would not read files owned by
 # another user.
-if test "$(id -i)" != "0"; then
+if test "$(id -u)" != "0"; then
     exit 77
 fi