setup: correctly reinitialize repository version

When reinitializing a repository, Git does not account for extensions
other than `objectformat` and `refstorage` when determining the
repository version. This can lead to a repository being downgraded to
version 0 if extensions are set, causing Git future operations to fail.

This patch teaches Git to check if other extensions are defined in the
config to ensure that the repository version is set correctly.

Signed-off-by: Caleb White <cdwhite3@pm.me>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: calebdw

setup.c

@@ -2204,8 +2204,8 @@ void initialize_repository_version(int hash_algo,
 				   enum ref_storage_format ref_storage_format,
 				   int reinit)
 {
-	char repo_version_string[10];
-	int repo_version = GIT_REPO_VERSION;
+	struct strbuf repo_version = STRBUF_INIT;
+	int target_version = GIT_REPO_VERSION;
 
 	/*
 	 * Note that we initialize the repository version to 1 when the ref
@@ -2216,12 +2216,7 @@ void initialize_repository_version(int hash_algo,
 	 */
 	if (hash_algo != GIT_HASH_SHA1 ||
 	    ref_storage_format != REF_STORAGE_FORMAT_FILES)
-		repo_version = GIT_REPO_VERSION_READ;
-
-	/* This forces creation of new config file */
-	xsnprintf(repo_version_string, sizeof(repo_version_string),
-		  "%d", repo_version);
-	git_config_set("core.repositoryformatversion", repo_version_string);
+		target_version = GIT_REPO_VERSION_READ;
 
 	if (hash_algo != GIT_HASH_SHA1 && hash_algo != GIT_HASH_UNKNOWN)
 		git_config_set("extensions.objectformat",
@@ -2234,6 +2229,25 @@ void initialize_repository_version(int hash_algo,
 			       ref_storage_format_to_name(ref_storage_format));
 	else if (reinit)
 		git_config_set_gently("extensions.refstorage", NULL);
+
+	if (reinit) {
+		struct strbuf config = STRBUF_INIT;
+		struct repository_format repo_fmt = REPOSITORY_FORMAT_INIT;
+
+		strbuf_git_common_path(&config, the_repository, "config");
+		read_repository_format(&repo_fmt, config.buf);
+
+		if (repo_fmt.v1_only_extensions.nr)
+			target_version = GIT_REPO_VERSION_READ;
+
+		strbuf_release(&config);
+		clear_repository_format(&repo_fmt);
+	}
+
+	strbuf_addf(&repo_version, "%d", target_version);
+	git_config_set("core.repositoryformatversion", repo_version.buf);
+
+	strbuf_release(&repo_version);
 }
 
 static int is_reinit(void)
@@ -2333,7 +2347,7 @@ static int create_default_files(const char *template_path,
 		adjust_shared_perm(repo_get_git_dir(the_repository));
 	}
 
-	initialize_repository_version(fmt->hash_algo, fmt->ref_storage_format, 0);
+	initialize_repository_version(fmt->hash_algo, fmt->ref_storage_format, reinit);
 
 	/* Check filemode trustability */
 	path = git_path_buf(&buf, "config");

t/t5504-fetch-receive-strict.sh

@@ -171,7 +171,7 @@ test_expect_success 'fsck with invalid or bogus skipList input' '
 	test_must_fail git -c fsck.skipList=does-not-exist -c fsck.missingEmail=ignore fsck 2>err &&
 	test_grep "could not open.*: does-not-exist" err &&
 	test_must_fail git -c fsck.skipList=.git/config -c fsck.missingEmail=ignore fsck 2>err &&
-	test_grep "invalid object name: \[core\]" err
+	test_grep "invalid object name: " err
 '
 
 test_expect_success 'fsck with other accepted skipList input (comments & empty lines)' '
@@ -234,7 +234,7 @@ test_expect_success 'push with receive.fsck.skipList' '
 	test_grep "could not open.*: does-not-exist" err &&
 	git --git-dir=dst/.git config receive.fsck.skipList config &&
 	test_must_fail git push --porcelain dst bogus 2>err &&
-	test_grep "invalid object name: \[core\]" err &&
+	test_grep "invalid object name: " err &&
 
 	git --git-dir=dst/.git config receive.fsck.skipList SKIP &&
 	git push --porcelain dst bogus
@@ -263,7 +263,7 @@ test_expect_success 'fetch with fetch.fsck.skipList' '
 	test_grep "could not open.*: does-not-exist" err &&
 	git --git-dir=dst/.git config fetch.fsck.skipList dst/.git/config &&
 	test_must_fail git --git-dir=dst/.git fetch "file://$(pwd)" $refspec 2>err &&
-	test_grep "invalid object name: \[core\]" err &&
+	test_grep "invalid object name: " err &&
 
 	git --git-dir=dst/.git config fetch.fsck.skipList dst/.git/SKIP &&
 	git --git-dir=dst/.git fetch "file://$(pwd)" $refspec