This patch further improves Drakma behavior in case of Redirect-to-Get 

Now Drakma doesn't change the method unless the method is supposed to change (probably, only POST should change).

The current behavior is unsatisfactory for example for HEAD requests. See a snippet of headers below:

    CL-USER> (drakma:http-request "http://sourceforge.net/projects/wnsql/files/wnsql-1.0.1/wordnet30-sqlite-1.0.1.zip/download" :method :head)
    HEAD /projects/wnsql/files/wnsql-1.0.1/wordnet30-sqlite-1.0.1.zip/download HTTP/1.1
    Host: sourceforge.net
    User-Agent: Drakma/1.3.0 (SBCL 1.0.55.0.debian; Linux; 3.2.0-23-generic; http://weitz.de/drakma/)
    Accept: */*
    Connection: close
    
    HTTP/1.1 302 Found
    Server: nginx/0.8.54
    Date: Wed, 10 Apr 2013 17:42:40 GMT
    Content-Type: text/html; charset=UTF-8
    Connection: close
    ....

    GET /project/wnsql/wnsql-1.0.1/wordnet30-sqlite-1.0.1.zip?r=&ts=1365615760&use_mirror=freefr HTTP/1.1
    ...