[Dune] certificate problems?

[Christian Engwer]

Dear all,

is there a problem with the server certificates, or am I just to
stupid to handle my git?

When I try to push to git.dune-project.org I receive the following
error message:

fatal: unable to access 'https://christi@git.dune-project.org/repositories/dune-common/': gnutls_handshake() failed: Public key signature verification has failed.

Christian