Review posted at https://illumos.org/rb/r/2340/

Testing:

% diff -u packages.i386{.old,}/osnet-incorporation.mog
--- packages.i386.old/osnet-incorporation.mog       Fri Sep 20 13:38:34 2019
+++ packages.i386/osnet-incorporation.mog   Fri Sep 20 13:38:34 2019
@@ -490,11 +490,12 @@
 depend fmri=pkg:/system/data/console/fonts@0.5.11,5.11-151030.0 \
     type=incorporate
 depend fmri=pkg:/system/data/hardware-registry@0.5.11,5.11-151030.0 \
-    type=incorporate
+    type=incorporate facet.version-lock.system/data/hardware-registry=true
 depend fmri=pkg:/system/data/keyboard/keytables@0.5.11,5.11-151030.0 \
     type=incorporate
 depend fmri=pkg:/system/data/terminfo@0.5.11,5.11-151030.0 type=incorporate
-depend fmri=pkg:/system/data/zoneinfo@2019.3,5.11-151030.0 type=incorporate
+depend fmri=pkg:/system/data/zoneinfo@2019.3,5.11-151030.0 type=incorporate \
+    facet.version-lock.system/data/zoneinfo=true
 depend fmri=pkg:/system/dtrace/tests@0.5.11,5.11-151030.0 type=incorporate
 depend fmri=pkg:/system/extended-system-utilities@0.5.11,5.11-151030.0 \
     type=incorporate

Notes from Andy in the RTI Mail¶

The osnet-incorporation effectively locks all incorporated packages together
at a specific version. As Rich notes, this is vital for some of them such as
libc and the kernel. For other packages, it would be useful to provide a
mechanism for an administrator to override the version lock.

The most recent case where this would have been useful was with the
system/data/zoneinfo package where the update to 2019c introduced a
regression. There was no way for an administrator to downgrade just this
package back to 2019a due to the incorporation.

For the system/data/hardware-registry package, the version has long been
deliberately left at 0.5.11 so as to allow downgrades if necessary. With this
change the next update to that package can use a proper release number.

This change adds the framework and initially adds version lock facets to
system/data/hardware-registry and system/data/zoneinfo as these are system
data files which are updated a couple of times a year. There may be other
packages that would benefit from this and they can be easily added in the
future. For example I think this would be useful for things like CPU microcode
too, but we will first need to split that out into separate packages.

Here's an example of this being used to downgrade system/data/zoneinfo.

bloody% pkg list -afv system/data/zoneinfo
FMRI                                                                         IFO
pkg://omnios/system/data/zoneinfo@2019.9-151033.0:20191210T090436Z           i--
pkg://omnios/system/data/zoneinfo@2019.3-151033.0:20191203T202512Z           ---

bloody% pfexec pkg update system/data/zoneinfo@2019.3
Creating Plan (Solver setup): /
pkg update: No matching version of system/data/zoneinfo can be installed:
  Reject:  pkg://omnios/system/data/zoneinfo@2019.3-151033.0
  Reason:  This version is excluded by installed incorporation consolidation/osnet/osnet-incorporation@0.5.11-151033.0

bloody% pkg facet -a | grep zoneinfo
version-lock.system/data/zoneinfo                                True  system

bloody% pfexec pkg change-facet version-lock.system/data/zoneinfo=False
            Packages to change:  1
     Variants/Facets to change:  1
...

bloody% pkg facet
FACET                                                            VALUE SRC
version-lock.system/data/zoneinfo                                False local

bloody% pfexec pkg update system/data/zoneinfo@2019.3
            Packages to update:  1
       Create boot environment: No
Create backup boot environment: No

PHASE                                          ITEMS
Installing new actions                           1/1
...

bloody% pkg list -afv system/data/zoneinfo
FMRI                                                                         IFO
pkg://omnios/system/data/zoneinfo@2019.9-151033.0:20191210T090436Z           ---
pkg://omnios/system/data/zoneinfo@2019.3-151033.0:20191203T202512Z           i--