pre-command: always respect core.hooksPath

We need to respect that config setting even if we already know that we
have a repository, but have not yet read the config.

The regression test was written by Alejandro Pauly.

2021-10-30: Recent movement of find_hook() into hook.c required moving this
change from run-command.c.

Signed-off-by: Johannes Schindelin <johasc@microsoft.com>

hook.c

@@ -66,9 +66,20 @@ const char *find_hook(const char *name)
 	int found_hook;
 
 	strbuf_reset(&path);
-	if (have_git_dir())
+	if (have_git_dir()) {
+		static int forced_config;
+
+		if (!forced_config) {
+			if (!git_hooks_path) {
+				git_config_get_pathname("core.hookspath",
+							&git_hooks_path);
+				UNLEAK(git_hooks_path);
+			}
+			forced_config = 1;
+		}
+
 		strbuf_git_path(&path, "hooks/%s", name);
-	else if (!hook_path_early(name, &path))
+	} else if (!hook_path_early(name, &path))
 		return NULL;
 
 	found_hook = access(path.buf, X_OK) >= 0;

t/t0400-pre-command-hook.sh

@@ -55,4 +55,15 @@ test_expect_success 'in a subdirectory, using an alias' '
 	test_line_count = 2 sub/log
 '
 
+test_expect_success 'with core.hooksPath' '
+	mkdir -p .git/alternateHooks &&
+	write_script .git/alternateHooks/pre-command <<-EOF &&
+	echo "alternate" >\$(git rev-parse --git-dir)/pre-command.out
+	EOF
+	write_script .git/hooks/pre-command <<-EOF &&
+	echo "original"	>\$(git rev-parse --git-dir)/pre-command.out
+	EOF
+	git -c core.hooksPath=.git/alternateHooks status &&
+	test "alternate" = "$(cat .git/pre-command.out)"
+'
 test_done