for-each-repo: work correctly in a worktree

When run in a worktree, the GIT_DIR directory is set in a different way
than in a typical repository. Show this by updating t0068 to include a
worktree and add a test that runs from that worktree. This requires
moving the repo.key config into a global config instead of the base test
repository's local config (demonstrating that it worked with
non-worktree Git repositories).

We need to be careful to unset the local Git environment variables and
let the child process rediscover them, while also reinstating those
variables in the parent process afterwards. Update run_command_on_repo()
to store, unset, then reset the non-NULL variables.

Reported-by: Matthew Gabeler-Lee <fastcat@gmail.com>
Signed-off-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: derrickstolee

builtin/for-each-repo.c

@@ -2,6 +2,7 @@
 
 #include "builtin.h"
 #include "config.h"
+#include "environment.h"
 #include "gettext.h"
 #include "parse-options.h"
 #include "path.h"
@@ -15,19 +16,45 @@ static const char * const for_each_repo_usage[] = {
 
 static int run_command_on_repo(const char *path, int argc, const char ** argv)
 {
-	int i;
+	int res;
 	struct child_process child = CHILD_PROCESS_INIT;
+	char **envvars;
+	size_t envvar_nr = 0;
 	char *abspath = interpolate_path(path, 0);
 
+	while (local_repo_env[envvar_nr])
+		envvar_nr++;
+
+	CALLOC_ARRAY(envvars, envvar_nr);
+
+	for (size_t i = 0; i < envvar_nr; i++) {
+		envvars[i] = getenv(local_repo_env[i]);
+
+		if (envvars[i]) {
+			unsetenv(local_repo_env[i]);
+			envvars[i] = xstrdup(envvars[i]);
+		}
+	}
+
 	child.git_cmd = 1;
 	strvec_pushl(&child.args, "-C", abspath, NULL);
 
-	for (i = 0; i < argc; i++)
+	for (int i = 0; i < argc; i++)
 		strvec_push(&child.args, argv[i]);
 
 	free(abspath);
 
-	return run_command(&child);
+	res = run_command(&child);
+
+	for (size_t i = 0; i < envvar_nr; i++) {
+		if (envvars[i]) {
+			setenv(local_repo_env[i], envvars[i], 1);
+			free(envvars[i]);
+		}
+	}
+
+	free(envvars);
+	return res;
 }
 
 int cmd_for_each_repo(int argc,

t/t0068-for-each-repo.sh

@@ -10,7 +10,7 @@ TEST_NO_CREATE_REPO=1
 test_expect_success 'run based on configured value' '
 	git init one &&
 	git init two &&
-	git init three &&
+	git -C two worktree add --orphan ../three &&
 	git init ~/four &&
 	git -C two commit --allow-empty -m "DID NOT RUN" &&
 	git config --global run.key "$TRASH_DIRECTORY/one" &&
@@ -35,7 +35,17 @@ test_expect_success 'run based on configured value' '
 	git -C three log -1 --pretty=format:%s >message &&
 	grep again message &&
 	git -C ~/four log -1 --pretty=format:%s >message &&
-	grep again message
+	grep again message &&
+
+	git -C three for-each-repo --config=run.key -- commit --allow-empty -m "ran from worktree" &&
+	git -C one log -1 --pretty=format:%s >message &&
+	grep worktree message &&
+	git -C two log -1 --pretty=format:%s >message &&
+	! grep worktree message &&
+	git -C three log -1 --pretty=format:%s >message &&
+	grep worktree message &&
+	git -C ~/four log -1 --pretty=format:%s >message &&
+	grep worktree message
 '
 
 test_expect_success 'do nothing on empty config' '