remote: set/unset the autotag setting on save

Make the configuration option match the configured behavior when
saving a remote.

src/remote.c

@@ -198,7 +198,9 @@ cleanup:
 
 int git_remote_save(const git_remote *remote)
 {
+	int error;
 	git_config *config;
+	const char *tagopt = NULL;
 	git_buf buf = GIT_BUF_INIT, value = GIT_BUF_INIT;
 
 	if (git_repository_config__weakptr(&config, remote->repo) < 0)
@@ -260,6 +262,38 @@ int git_remote_save(const git_remote *remote)
 			goto on_error;
 	}
 
+	/*
+	 * What action to take depends on the old and new values. This
+	 * is describes by the table below. tagopt means whether the
+	 * is already a value set in the config
+	 *
+	 *            AUTO     ALL or NONE
+	 *         +-----------------------+
+	 *  tagopt | remove  |     set     |
+	 *         +---------+-------------|
+	 * !tagopt | nothing |     set     |
+	 *         +---------+-------------+
+	 */
+
+	git_buf_clear(&buf);
+	if (git_buf_printf(&buf, "remote.%s.tagopt", remote->name) < 0)
+		goto on_error;
+
+	error = git_config_get_string(&tagopt, config, git_buf_cstr(&buf));
+	if (error < 0 && error != GIT_ENOTFOUND)
+		goto on_error;
+
+	if (remote->download_tags == GIT_REMOTE_DOWNLOAD_TAGS_ALL) {
+		if (git_config_set_string(config, git_buf_cstr(&buf), "--tags") < 0)
+			goto on_error;
+	} else if (remote->download_tags == GIT_REMOTE_DOWNLOAD_TAGS_NONE) {
+		if (git_config_set_string(config, git_buf_cstr(&buf), "--no-tags") < 0)
+			goto on_error;
+	} else if (tagopt) {
+		if (git_config_delete(config, git_buf_cstr(&buf)) < 0)
+			goto on_error;
+	}
+
 	git_buf_free(&buf);
 	git_buf_free(&value);
 

tests-clar/network/remotes.c

@@ -225,3 +225,27 @@ void test_network_remotes__add(void)
 	cl_assert(!strcmp(git_refspec_dst(_refspec), "refs/remotes/addtest/*"));
 	cl_assert_equal_s(git_remote_url(_remote), "http://github.com/libgit2/libgit2");
 }
+
+void test_network_remotes__tagopt(void)
+{
+	const char *opt;
+	git_config *cfg;
+
+	cl_git_pass(git_repository_config(&cfg, _repo));
+
+	git_remote_set_autotag(_remote, GIT_REMOTE_DOWNLOAD_TAGS_ALL);
+	cl_git_pass(git_remote_save(_remote));
+	cl_git_pass(git_config_get_string(&opt, cfg, "remote.test.tagopt"));
+	cl_assert(!strcmp(opt, "--tags"));
+
+	git_remote_set_autotag(_remote, GIT_REMOTE_DOWNLOAD_TAGS_NONE);
+	cl_git_pass(git_remote_save(_remote));
+	cl_git_pass(git_config_get_string(&opt, cfg, "remote.test.tagopt"));
+	cl_assert(!strcmp(opt, "--no-tags"));
+
+	git_remote_set_autotag(_remote, GIT_REMOTE_DOWNLOAD_TAGS_AUTO);
+	cl_git_pass(git_remote_save(_remote));
+	cl_assert(git_config_get_string(&opt, cfg, "remote.test.tagopt") == GIT_ENOTFOUND);
+
+	git_config_free(cfg);
+}