The Software Update Stack was updated to receive fixes and enhancements.

libzypp:

- Adapt to work with GnuPG 2.1.23. (bsc#1054088)
- Support signing with subkeys. (bsc#1008325)
- Enhance sort order for media.1/products. (bsc#1054671)
- Add enum GpgCheck for convenient gpgcheck mode handling. (bsc#1045735)
- Fix repo/pkg checks to follow explicitly defined gpgcheck in a .repo file.

zypper:

- Also show a gpg key's subkeys. (bsc#1008325)
- Improve signature check callback messages. (bsc#1045735)
- Add options to tune the GPG check settings. (bsc#1045735)

This update was imported from the SUSE:SLE-12-SP2:Update update project.