nginx and API versioning in Accept header or URL - nginx

Question

So I have decided to do two kind of wrong, slightly inspired by Troy Hunt.
I would like my API to accept version specification through Accept header but also in the URL, e.g. /v1.
For now, I have made an nginx config which works with Accept header, but trying out various methods, I have not been able to get the /v1
What I want to achieve is that the URL passed to my application, does not include the version part as the role of the version is simply to point at a root directory.
map $http_accept $api_version {
default 0;
"application/vnd.it.echo.api+json; version=1" "v1";
}
server {
listen 80;
server_name api.app;
index index.html index.htm index.php;
charset utf-8;
sendfile off;
rewrite_log on;
location = /favicon.ico { access_log off; log_not_found off; }
location = /robots.txt { access_log off; log_not_found off; }
location / {
if ($api_version = 0) {
return 307 https://echo.it;
}
try_files $uri $uri/ #api;
}
location /v1 {
set $api_version "v1";
rewrite ^/.+/(.+)$ /$1 last;
}
location #api {
root /home/vagrant/api/$api_version/public/;
error_log /var/log/nginx/api.$api_version.app-error.log error;
try_files $uri $uri/ /index.php?$query_string;
}
error_page 404 /index.php;
location ~ \.php$ {
root /home/vagrant/api/$api_version/public/;
fastcgi_split_path_info ^(.+\.php)(/.+)$;
fastcgi_pass unix:/var/run/php5-fpm.sock;
fastcgi_index index.php;
include fastcgi_params;
}
location ~ /\.ht {
deny all;
}
}
The problem appears to be with the rewrite rule in the /v1 location directive not taking effect.