environment: move "branch.autoSetupMerge" into struct repo_config_values

The config value `brach.autoSetupMerge` is parsed in
`git_default_branch_config()` and stored in the global variable
`git_branch_track`. This global variable can cause unexpected behaviours
when multiple Git repos run in the the same process.

Move this value into `struct repo_config_values` which holds all values
parsed by `git_default_config()` and can be accessed per
repo via `git_default_config()`. This would retain the same
behaviours while achieving repository scoped access.

Suggested-by: Phillip Wood <phillip.wood123@gmail.com>
Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Usman Akinyemi <usmanakinyemi202@gmail.com>
Signed-off-by: Olamide Caleb Bello <belkid98@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

branch.h

@@ -15,8 +15,6 @@ enum branch_track {
 	BRANCH_TRACK_SIMPLE,
 };
 
-extern enum branch_track git_branch_track;
-
 /* Functions for acting on the information about branches. */
 
 /**

builtin/branch.c

@@ -795,7 +795,7 @@ int cmd_branch(int argc,
 	if (!sorting_options.nr)
 		string_list_append(&sorting_options, "refname");
 
-	track = git_branch_track;
+	track = the_repository->config_values.git_branch_track;
 
 	head = refs_resolve_refdup(get_main_ref_store(the_repository), "HEAD",
 				   0, &head_oid, NULL);

builtin/checkout.c

@@ -1631,7 +1631,7 @@ static int checkout_branch(struct checkout_opts *opts,
 		if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 			die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
 	} else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
-		opts->track = git_branch_track;
+		opts->track = the_repository->config_values.git_branch_track;
 
 	if (new_branch_info->name && !new_branch_info->commit)
 		die(_("Cannot switch branch to a non-commit '%s'"),

builtin/push.c

@@ -162,7 +162,7 @@ static NORETURN void die_push_simple(struct branch *branch,
 		advice_pushdefault_maybe = _("\n"
 				 "To choose either option permanently, "
 				 "see push.default in 'git help config'.\n");
-	if (git_branch_track != BRANCH_TRACK_SIMPLE)
+	if (the_repository->config_values.git_branch_track != BRANCH_TRACK_SIMPLE)
 		advice_automergesimple_maybe = _("\n"
 				 "To avoid automatically configuring "
 				 "an upstream branch when its name\n"

builtin/submodule--helper.c

@@ -3128,7 +3128,7 @@ static int module_create_branch(int argc, const char **argv, const char *prefix,
 	};
 
 	repo_config(the_repository, git_default_config, NULL);
-	track = git_branch_track;
+	track = the_repository->config_values.git_branch_track;
 	argc = parse_options(argc, argv, prefix, options, usage, 0);
 
 	if (argc != 3)

environment.c

@@ -66,7 +66,6 @@ enum auto_crlf auto_crlf = AUTO_CRLF_FALSE;
 enum eol core_eol = EOL_UNSET;
 int global_conv_flags_eol = CONV_EOL_RNDTRP_WARN;
 char *check_roundtrip_encoding;
-enum branch_track git_branch_track = BRANCH_TRACK_REMOTE;
 enum rebase_setup_type autorebase = AUTOREBASE_NEVER;
 enum push_default_type push_default = PUSH_DEFAULT_UNSPECIFIED;
 #ifndef OBJECT_CREATION_MODE
@@ -607,18 +606,20 @@ static int git_default_i18n_config(const char *var, const char *value)
 
 static int git_default_branch_config(const char *var, const char *value)
 {
+	struct repo_config_values *cfg = &the_repository->config_values;
+
 	if (!strcmp(var, "branch.autosetupmerge")) {
 		if (value && !strcmp(value, "always")) {
-			git_branch_track = BRANCH_TRACK_ALWAYS;
+			cfg->git_branch_track = BRANCH_TRACK_ALWAYS;
 			return 0;
 		} else if (value && !strcmp(value, "inherit")) {
-			git_branch_track = BRANCH_TRACK_INHERIT;
+			cfg->git_branch_track = BRANCH_TRACK_INHERIT;
 			return 0;
 		} else if (value && !strcmp(value, "simple")) {
-			git_branch_track = BRANCH_TRACK_SIMPLE;
+			cfg->git_branch_track = BRANCH_TRACK_SIMPLE;
 			return 0;
 		}
-		git_branch_track = git_config_bool(var, value);
+		cfg->git_branch_track = git_config_bool(var, value);
 		return 0;
 	}
 	if (!strcmp(var, "branch.autosetuprebase")) {
@@ -756,3 +757,8 @@ int git_default_config(const char *var, const char *value,
 	/* Add other config variables here and to Documentation/config.adoc. */
 	return 0;
 }
+
+void repo_config_values_init(struct repo_config_values *cfg)
+{
+	cfg->git_branch_track = BRANCH_TRACK_REMOTE;
+}

environment.h

@@ -2,6 +2,7 @@
 #define ENVIRONMENT_H
 
 #include "repo-settings.h"
+#include "branch.h"
 
 /* Double-check local_repo_env below if you add to this list. */
 #define GIT_DIR_ENVIRONMENT "GIT_DIR"
@@ -89,6 +90,9 @@ struct repo_config_values {
 	/* core config values */
 	char *attributes_file_path;
 	int sparse_checkout;
+
+	/* branch config values */
+	enum branch_track git_branch_track;
 };
 
 /*
@@ -114,6 +118,8 @@ const char *strip_namespace(const char *namespaced_ref);
 int git_default_config(const char *, const char *,
 		       const struct config_context *, void *);
 
+void repo_config_values_init(struct repo_config_values *cfg);
+
 /*
  * TODO: All the below state either explicitly or implicitly relies on
  * `the_repository`. We should eventually get rid of these and make the

repository.c

@@ -57,6 +57,7 @@ void initialize_repository(struct repository *repo)
 	ALLOC_ARRAY(repo->index, 1);
 	index_state_init(repo->index, repo);
 	repo->check_deprecated_config = true;
+	repo_config_values_init(&repo->config_values);
 
 	/*
 	 * When a command runs inside a repository, it learns what