This update for charliecloud fixes the following issues:

Update to version 0.22.

- “ch-image” can now push images to a registry, with the “push” subcommand
- As a reminder, “ch-grow” has been renamed to “ch-image”.
The old name still works but will be removed in 0.23.
- ch-image: new subcommand “delete”
- ch-image pull:
* now keeps some metadata from pulled image
* now works with public images in nVidia NGC registry
* setuid/setgid bits in pulled image now cleared
* performance improvements for images with many whiteouts
- ch-image build:
* environment variables now kept from base image
* SHELL instruction now supported
- several scripts now work correctly if image name contains slash
- “sudo make install” now works correctly with restrictive umasks
- miscellaneous bug fixes and improvements

Update to version 0.21.

- renamed the internal builder ch-grow to ch-image to reflect
its broader functionality. ch-grow still works but will be
deprecated in 0.23
- ch-image unprivileged build workarounds using fakeroot
now default to off and must be requested with --force;
the option --no-fakeroot has been removed. ch-image will
by default print a warning if it thinks --force might fix
a build failure.
- ch-image pull now works with registries that use HTTP basic auth
and with images that use manifest schema version 1.
- ch-image build has a new option --bind to bind-mount directories
during build and COPY: improve symlink and directory handling
- miscellaneous bug fixes and improvements
- Full changelog at https://groups.io/g/charliecloud/message/108

Update to version 0.20.

- improvement for unprivileged image build using fakeroot
This feature can be turned off with “ch-grow build --no-fakeroot”
Further details are in the ch-grow man page
- miscellaneous bug fixes and improvements
- Full changelot at https://groups.io/g/charliecloud/message/107

Update to version 0.19. Two particularly notable changes:

- ch-grow now supports multi-stage build (#768), which as always
is fully unprivileged. This represents a big step forward in
functionality.
- ch-grow now has subcommands; what used to be plain ch-grow
is now ch-grow build, and ch-tug has become ch-grow pull.
- miscellaneous bug fixes and improvements
- Full changelog at https://groups.io/g/charliecloud/message/106