nginx配置location时，不能完全匹配路径

[PHP编程者]

我有个域名 www.xxx.com
目的：正常访问时指向目录A（/home/a），当url中含路径/v3/时指向目录B（/home/b）
但下面的配置，当我访问 www.xxx.com/v3/时指向目录B，但访问www.xxx.com/v3/home时却指向了目录A
问题出在哪呢？
配置如下：

server {
       listen       80;
        server_name  www.xxx.com;

        access_log  /var/log/nginx/qhq/qhq_bool_tmp_access.log main;
        error_log /var/log/nginx/qhq/qhq_bool_tmp_error.log debug;

        set $web_root /home/a;

        location ^~ /v3/ {
            alias /home/b/;
            index  index.html index.htm index.php;

            location ~ \.php$ {
                fastcgi_pass   127.0.0.1:9000;
                fastcgi_index  index.php;
                fastcgi_param  SCRIPT_FILENAME  $request_filename;
                include        fastcgi_params;
            }
        }

        location / {
            root   $web_root;
            index  index.html index.htm index.php;
            if (!-f $request_filename) {
            rewrite (.*) /index.php last;
            }
        }

        error_page  404              /404.html;

        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   $web_root;
        }


        location ~ \.php$ {
            root           $web_root;
            fastcgi_pass   127.0.0.1:9000;
            fastcgi_index  index.php;
            fastcgi_param  SCRIPT_FILENAME  $web_root/$fastcgi_script_name;
            include        fastcgi_params;
        }

        location ~ /\. {
            deny all;
        access_log off;
            log_not_found off;
     }

}

[孟子E章]

我测试了是可以的。 location ^~ /v3/ { alias /home/b/; index index.html index.htm index.php; location ~ \.php$ { fastcgi_pass 127.0.0.1:9000; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $request_filename; include fastcgi_params; } } location 可以嵌套？

[PHP编程者]

好像可以嵌套