execve failed for: /.../public/dispatch.fcgi No such file or directory

SVNからさるRailsアプリを落としてきてdatabase.ymlを修正した後、./script/serverするとさっくりエラー

% ./script/server
=> Booting lighttpd (use 'script/server webrick' to force WEBrick)
=> Rails application starting on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server (see config/lighttpd.conf for options)
2008-02-02 00:09:55: (mod_fastcgi.c.988) execve failed for: /.../public/dispatch.fcgi No such file or directory
2008-02-02 00:09:55: (mod_fastcgi.c.1014) the fastcgi-backend /.../public/dispatch.fcgi failed to start:
2008-02-02 00:09:55: (mod_fastcgi.c.1018) child exited with status 2 /.../public/dispatch.fcgi
2008-02-02 00:09:55: (mod_fastcgi.c.1021) if you try do run PHP as FastCGI backend make sure you use the FastCGI enabled version.
You can find out if it is the right one by executing 'php -v' and it should display '(cgi-fcgi)' in the output, NOT (cgi) NOR (cli)
For more information check http://www.lighttpd.net/documentation/fastcgi.html#preparing-php-as-a-fastcgi-program
2008-02-02 00:09:55: (mod_fastcgi.c.1026) If this is PHP on Gentoo add fastcgi to the USE flags
2008-02-02 00:09:55: (mod_fastcgi.c.1322) [ERROR]: spawning fcgi failed.
2008-02-02 00:09:55: (server.c.849) Configuration of plugins failed. Going down.
Exiting

ファイルは普通にあるし、PHPとか使ってないし、ワケわかんないなーと思ったんだけど、理由はdispatch.fcgiの一行目だった。shebangを間違ってるとこんなヘンテコエラーになるんだ。しらなんだ。