Bug in cURL causing Git authentication errors

There seems to be a problem with https authentication. The problem occurs when cloning my private repository. It basically seems to boil down to this

1. git makes a GET request via curl
2. bitbucket.org responds with 401 unauthorized and a WWW-Authenticate header field
3. git makes a second GET request with proper Authorization header set
4. bitbucket.org responds with 200 OK (and empty content?)
5. git makes a POST git-upload-pack request
6. bitbucket.org again responds with 401 header and WWW-Authenticate header field
7. git exits with error: RPC failed; result=22, HTTP code = 401

full log (stripped of sensitive information) is attached