# instead of:
location ~ ^/foo(/?)(bar.*)$ {
    proxy_set_header X-Forwarded-Host $host;
    proxy_set_header X-Forwarded-Server $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_redirect ~^http://backend/(.*)$ https://$host/$1;
    proxy_pass http://backend;
}

location ~ ^/foo(/?)(.*)$ {
    proxy_set_header X-Forwarded-Host $host;
    proxy_set_header X-Forwarded-Server $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_redirect ~^http://backend/(.*)$ https://$host/$1;
    proxy_pass http://backend;
}


# Do this:
location /foo {
  location ~ ^/foo(/?)(bar.*)$ {
      proxy_set_header X-Forwarded-Host $host;
      proxy_set_header X-Forwarded-Server $host;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_redirect ~^http://backend/(.*)$ https://$host/$1;
      proxy_pass http://backend;
  }

  location ~ ^/foo(/?)(.*)$ {
      proxy_set_header X-Forwarded-Host $host;
      proxy_set_header X-Forwarded-Server $host;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_redirect ~^http://backend/(.*)$ https://$host/$1;
      proxy_pass http://backend;
  }
}