clone a git repository on bitbucket from Egit+Eclipse behind a firewall via a HTTPS proxy

If you try to clone a repository on via HTTPS proxy with Egit + Eclipse, you get an error

Problem Occurred
Git repository clone failed. -1 null

at the "Cloning from ... " step.

There is a workaround which is not very secure. Add an entry http.sslverify=>false in
Eclipse > Preferences > Team > Git > Configuration > User Settings.