Fetching gem metadata from https://rubygems.org/…
Your bundle is locked to mimemagic (0.3.3), but that version could not be found
in any of the sources listed in your Gemfile. If you haven’t changed sources,
that means the author of mimemagic (0.3.3) has removed it. You’ll need to update
your bundle to a version other than mimemagic (0.3.3) that hasn’t been removed
in order to install.
ERROR: Service ‘sync’ failed to build: The command ‘/bin/sh -c bundle install --jobs 20 --retry 5 --without development test’ returned a non-zero code: 7
make: *** [setup] Error 1