Pypi Repository Package 400 bad request when pushing a new python lib

ok, I got a solution for me, now.
There where two problems:

1. a default twine call tries to curl the https address. The port at the server side can behave different compared to what is expected.
2. in /etc/gitlab/gitlab.rb there was a line, stating something like
   gitlab_workhorse[‘listen_addr’] = …
   which didn’t work as long as the value was
   127.0.0.1:8181
   instead
   0.0.0.0:8181
   helped.