Given the request to http://127.0.0.1/cgit/xyz/ and the relevant resulting request headers as follows::
DOCUMENT_ROOT=/var/www/localhost/htdocs/cgit/
SCRIPT_FILENAME=/var/www/localhost/htdocs/cgit/tst
REQUEST_URI=/cgit/xyz/
SCRIPT_NAME=tst
... no PATH_INFO is set.

Expected is PATH_INFO /xyz/ or similar.

You can easily test that by this CGI script::
#!/bin/sh
echo Content-type: text/plain
echo Expires: 0
echo ""
/bin/env
/bin/date