DoS on wrong password

As discussed in upstream bug report saltstack/salt#38230 pygit2 tries to authenticate indefinite with wrong credentials instead of failing after two consecutive failures with same authentication token as specified by https://tools.ietf.org/html/rfc7235#section-3.1
Possible a libgit2 Bug if it's reproducable with other language bindings.

Testcase:

nginx dummy server configuration

This is just a stub configuration, no real repository needed

location ~ /git(/.*) {
        add_header "WWW-Authenticate" "Basic realm=\"Closed Areas\"" always;
        return 401;
    }

test client

#!/bin/python2.7

import pygit2

username = 'dummyUser'
password = 'dummyPassword'
credentials = pygit2.UserPass(username, password)
callbacks = pygit2.RemoteCallbacks(credentials)
pygit2.clone_repository("http://git.demo.local/git/test.git", "test.git", bare=True, callbacks=callbacks)

Start with the Python testcase using pygit2.UserPass, pygit2.RemoteCallbacks, and pygit2.clone_repository against the supplied nginx configuration. Reproduce the repeated authentication attempts and compare the behavior with RFC 7235 section 3.1. Done means the clone fails after two consecutive failures with the same authentication token, while confirming whether the behavior is specific to pygit2 or libgit2.