sylabs/singularity: Singularity 3.5.3 Release Candidate 1

This is the first release candidate for the upcoming Singularity 3.5.3 - a bugfix release with the following changes and fixes: Changed defaults / behaviours The following minor behaviour changes have been made in 3.5.3 to allow correct operation on CRAY CLE6, and correct an issue with multi-stage image builds that was blocking use by build systems such as Spack: Container action scripts are no longer bound in from etc/actions.d on the host. They are created dynamically and inserted at container startup. %files from ... will no longer follow symlinks when copying between stages in a multi stage build, as symlinks should be copied so that they resolve identically in later stages. Copying %files from the host will still maintain previous behavior of following links. Bug Fixes Bind additional CUDA 10.2 libs when using the --nv option without nvidia-container-cli. Fix an NVIDIA persistenced socket bind error with --writable. Add detection of ceph to allow workarounds that avoid issues with sandboxes on ceph filesystems. Ensure setgid is inherited during make install. Ensure the root directory of a build has owner write permissions, regardless of the permissions in the bootstrap source. Fix a regression in %post and %test to honor the -c option. Fix an issue running %post when a container doesn't have /etc/resolv.conf or /etc/hosts files. Fix an issue with UID detection on RHEL6 when running instances. Fix a logic error when a sandbox image is in an overlay incompatible location, and both overlay and underlay are disabled globally. Fix an issue causing user namespace to always be used when allow-setuid=no was configured in a setuid installation. Always allow key IDs and fingerprints to be specified with or without a 0x prefix when using singularity keys Fix an issue preventing joining an instance started with --boot. In addition, numerous improvements have been made to the test suites, allowing them to pass cleanly on a range of kernel versions and distributions that are not covered by the open-source CI runs. Many thanks to those who have contributed code, bug reports, and testing! If you are able to test this release candidate in your environment, and report any issues, it will greatly assist us in delivering a great 3.5.3 release. As always, please report any bugs to: https://github.com/sylabs/singularity/issues/new If you think that you've discovered a security vulnerability please report it to: security@sylabs.i