Topic choice pulldown menu

[RomanSyunyaev]

Topic choice pulldown menu doesn't work. Leaksanitizer errors on the server, empty respsonse to the client after chosing the topic. Stderr log is attached.
Steps to reproduce:

1. $ uwsgi-core --plugins http,cgi --http-socket :7542 --cgi . --cgi-allowed-ext .cgi --http-socket-modifier1 9 --check-static static 2>log.txt
2. Click "Выберите тему" on the upper right corner.
3. Choose "Развлечения" (or any topic you like).
   log.txt