Git cloning does not work on the Docker images

I constantly get this kind of errors, which works everywhere else using the same recipes:

Command '['/opt/miniconda/bin/git', 'clone', '--mirror', 'https://github.com/menpo/menpowidgets.git', '/builds/bob/bob.conda/conda-env/git_cache/github.com/menpo/menpowidgets.git']' returned non-zero exit status 128

@amohammadi: could you please check?

Example build where it FAILS: https://gitlab.idiap.ch/bob/bob.conda/builds/42680

Example build where it goes OK (on OSX): https://gitlab.idiap.ch/bob/bob.conda/builds/42681

I think the problem is related to git cloning an https source (github). Is curl and certificates correctly setup on this image?