We released a new version of repo2docker 
!
To install it:
pip install --upgrade jupyter-repo2docker
The headline change is that re-builds of a repository will be super fast now if all you did is change content, not the dependencies. We currently support requirements.txt, environment.yml and install.R for “fast rebuilds”.
We also updated conda which means you will benefit from the work the conda team has done to speed it up.
Another exciting new feature is that you can directly build your image from a Zenodo (or other Invenio instance) DOI! repo2docker <your-zenodo-DOI-here>
In general the focus was on speeding up the build process and slimming down the resulting images. Thanks to everyone who pitched in with ideas, testing, feedback, examples and code!
You can find the full change log here.
Changes are deployed to mybinder.org as they get merged, so you might have already used some of the new features without knowing it 