git clone https://github.com/xurenlu/acfilter.git

Cloning into ‘acfilter’…

error: SSL certificate problem, verify that the CA cert is OK. Details:

error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed while accessing https://github.com/xurenlu/acfilter.git/info/refs

fatal: HTTP request failed

a workaround is to tell git to avoid checking SSL certificates:

export GIT_SSL_NO_VERIFY=true

reference