The commit-graph tests should be checking that normal Git operations
succeed and have matching output with and without the commit-graph
feature enabled. However, the test was toggling 'core.graph' instead
of the correct 'core.commitGraph' variable.
Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>