This is a bugfix release. It fixes a problem in 4.3.15 which caused the command hash table to take a long time to build on systems with commands stored on the network. 4.3.16 was not widely announced, and anyone upgrading should go straight to 4.3.17.
This release fixes a significant bug in process management in POSIX compatibility mode reported since 4.3.14, although the problem has been present since 4.3.10.
This is a bugfix release for the 4.3 development branch; there are no significant new features, although there are the usual improvements to completion and other shell functions.