hooks: change postCommand.strategy config value

The previously-named 'post-index-change' value for
'postCommand.strategy' did the following two things:

 1. Avoid running the post-command hook unless the post-index-change
    hook _would_ run with a signal that the worktree changed.

 2. Avoid running any installed post-index-change hooks.

The additional restriction of the worktree change in (1) makes this name
less appropriate. Also, item (2) seems to be a side-effect that we
should avoid. We would like to allow both behaviors to exist.

Update the value and behavior, including the tests.

Signed-off-by: Derrick Stolee <stolee@gmail.com>

Author: derrickstolee

Documentation/config/postcommand.adoc

@@ -7,7 +7,7 @@ postCommand.strategy::
 `always`;;
 	run the `post-command` hook on every process (default).
 
-`post-index-change`;;
+`worktree-change`;;
 	run the `post-command` hook only if the current process wrote to
 	the index and updated the worktree.
 ----

hook.c

@@ -246,7 +246,7 @@ static int handle_hook_replacement(struct repository *r,
 {
 	const char *strval;
 	if (repo_config_get_string_tmp(r, "postcommand.strategy", &strval) ||
-	    strcasecmp(strval, "post-index-change"))
+	    strcasecmp(strval, "worktree-change"))
 		return 0;
 
 	if (!strcmp(hook_name, "post-index-change")) {
@@ -255,10 +255,13 @@ static int handle_hook_replacement(struct repository *r,
 			*result = write_post_index_change_sentinel(r);
 		else
 			*result = 0;
-		return 1;
+
+		/* We don't skip post-index-change hooks that exist. */
+		return 0;
 	}
 	if (!strcmp(hook_name, "post-command") &&
 	    !post_index_change_sentinel_exists(r)) {
+		/* We skip the post-command hook in this case. */
 		*result = 0;
 		return 1;
 	}

t/t0401-post-command-hook.sh

@@ -63,24 +63,26 @@ test_expect_success 'with post-index-change config' '
 	test_cmp expect post-command.out &&
 
 	# Now, show configured behavior
-	git config postCommand.strategy post-index-change &&
-	rm -f post-command.out post-index-change.out &&
+	git config postCommand.strategy worktree-change &&
 
 	# rev-parse leaves index intact and thus skips post-command.
+	rm -f post-command.out post-index-change.out &&
 	git rev-parse HEAD &&
 	test_path_is_missing post-index-change.out &&
 	test_path_is_missing post-command.out &&
 
 	echo stuff >>file &&
 	# add keeps the worktree the same, so does not run post-command.
+	rm -f post-command.out post-index-change.out &&
 	git add file &&
-	test_path_is_missing post-index-change.out &&
+	test_cmp expect post-index-change.out &&
 	test_path_is_missing post-command.out &&
 
 	echo stuff >>file &&
 	# reset --hard updates the worktree.
+	rm -f post-command.out post-index-change.out &&
 	git reset --hard &&
-	test_path_is_missing post-index-change.out &&
+	test_cmp expect post-index-change.out &&
 	test_cmp expect post-command.out
 '