The idea of the magic value "ac4f2ee" in this test is to make the reworded commit `collide2` have the same shortened ID as the commit `collide3`. To port the same idea to the SHA-256 version of Git, we therefore need another magic value that causes the same collision, but this time with the SHA-256 version of the commit IDs. In this patch, we add code guarded by `GIT_TEST_FIND_COLLIDER` to do exactly that. Essentially, a large number of integers is appended to the commit message "collide2" to find such a collision. To make it easier to find such a collision, we reduce the number of digits to 4. As the tests are no longer dependent on SHA-1, we also rename their titles to talk about "commit IDs" instead of "SHA-1s". Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Reviewed-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>