git: Remove handling for GIT_PREFIX

handle_alias() no longer needs to set GIT_PREFIX since it is defined
in setup_git_directory_gently().  Remove the duplicated effort and use
run_command_v_opt() since there is no need to setup the environment.

Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git.c

@@ -179,8 +179,6 @@ static int handle_alias(int *argcp, const char ***argv)
 		if (alias_string[0] == '!') {
 			const char **alias_argv;
 			int argc = *argcp, i;
-			struct strbuf sb = STRBUF_INIT;
-			const char *env[2];
 
 			commit_pager_choice();
 
@@ -191,13 +189,7 @@ static int handle_alias(int *argcp, const char ***argv)
 				alias_argv[i] = (*argv)[i];
 			alias_argv[argc] = NULL;
 
-			strbuf_addstr(&sb, "GIT_PREFIX=");
-			if (subdir)
-				strbuf_addstr(&sb, subdir);
-			env[0] = sb.buf;
-			env[1] = NULL;
-			ret = run_command_v_opt_cd_env(alias_argv, RUN_USING_SHELL, NULL, env);
-			strbuf_release(&sb);
+			ret = run_command_v_opt(alias_argv, RUN_USING_SHELL);
 			if (ret >= 0)   /* normal exit */
 				exit(ret);