先贴出我的server配置：

server {
    listen 80;
    server_name xxx; 
    # 1
    location = /favicon.ico {
        root /home/www-data/static;
        rewrite (.*) /img/designs/admin-favicon.ico;
    }
    #2
    location = /robots.txt {
        root /home/www-data/static;
        rewrite (.*) /admin-robots.txt;
    }
    # 3
    location / {
        proxy_pass_header Server;
        proxy_set_header Host $http_host;
        proxy_redirect off;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Scheme $scheme;
        proxy_pass http://127.0.0.1:22222;
     }
}

官方给出的location搜索路径优先级和算法描述如下：

To find location matching a given request, nginx first checks
locations defined using the prefix strings (prefix locations). Among
them, the location with the longest matching prefix is selected and
remembered. Then regular expressions are checked, in the order of
their appearance in the configuration file. The search of regular
expressions terminates on the first match, and the corresponding
configuration is used. If no match with a regular expression is found
then the configuration of the prefix location remembered earlier is
used.

按照我的理解，Nginx搜索的时候算法应该是这样的：

1. 按照请求前缀搜索location最长普通前缀匹配（如果有=修饰符，则直接匹配该location，如果有^~修饰符，则直接使用该location），记住最长匹配location。
2. 继续按照配置顺序搜索正则匹配，如果有，则直接匹配第一个匹配到的location，否则使用普通最长location

也就说，按照我的配置，浏览器请求/favicon.ico的时候，应该是直接精准匹配到
1 才对啊，可是每次都匹配到 3。
这里请教一下各位，我对Nginx location的理解有没有偏差？然后为什么我的配置会是这样的结果？