test_git_colocated_fetch_deleted_branch: Fix the test

Before, HEAD@git was at change `e1f4` mentioned in the test. So, as long as we
consider the behavior added in 20eb9ec to be correct, that change should NOT
have been abandoned after the fetch, in spite of what the comment in the test
says. In other words, the test did NOT demonstrate a bug before this commit.

Now, the test properly demonstrates the bug.

Cc jj-vcs#864

tests/test_git_colocated.rs

@@ -248,10 +248,12 @@ fn test_git_colocated_fetch_deleted_branch() {
     let clone_path = test_env.env_root().join("clone");
     git2::Repository::clone(origin_path.to_str().unwrap(), &clone_path).unwrap();
     test_env.jj_cmd_success(&clone_path, &["init", "--git-repo=."]);
+    test_env.jj_cmd_success(&clone_path, &["new", "A"]);
     insta::assert_snapshot!(get_log_output(&test_env, &clone_path), @r###"
-    @  bc7d08e8de9b7bc248b9358a05e96f1671bbd4d9
-    ◉  e1f4268fabd2c84e880c5eb5bd87e076180fc8e3 B HEAD@git
-    ◉  a86754f975f953fa25da4265764adc0c62e9ce6b A master
+    @  1fa8b2e27c8c3da9764bda953dd81a06fb292d1a
+    │ ◉  e1f4268fabd2c84e880c5eb5bd87e076180fc8e3 B
+    ├─╯
+    ◉  a86754f975f953fa25da4265764adc0c62e9ce6b A master HEAD@git
     ◉  0000000000000000000000000000000000000000
     "###);
 
@@ -260,9 +262,10 @@ fn test_git_colocated_fetch_deleted_branch() {
     insta::assert_snapshot!(stdout, @"");
     // TODO: e1f4 should have been abandoned (#864)
     insta::assert_snapshot!(get_log_output(&test_env, &clone_path), @r###"
-    @  bc7d08e8de9b7bc248b9358a05e96f1671bbd4d9
-    ◉  e1f4268fabd2c84e880c5eb5bd87e076180fc8e3  HEAD@git
-    ◉  a86754f975f953fa25da4265764adc0c62e9ce6b A master
+    @  1fa8b2e27c8c3da9764bda953dd81a06fb292d1a
+    │ ◉  e1f4268fabd2c84e880c5eb5bd87e076180fc8e3
+    ├─╯
+    ◉  a86754f975f953fa25da4265764adc0c62e9ce6b A master HEAD@git
     ◉  0000000000000000000000000000000000000000
     "###);
 }