zpool upgrade can't enable new features

[Renato Botelho]

I recently upgraded a CURRENT system to main-n244932-248a47a4c2f and 
zpool status shows:

   pool: zroot
  state: ONLINE
status: Some supported and requested features are not enabled on the pool.
         The pool can still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
         the pool may no longer be accessible by software that does not 
support
         the features. See zpool-features(5) for details.
config:

         NAME        STATE     READ WRITE CKSUM
         zroot       ONLINE       0     0     0
           raidz2-0  ONLINE       0     0     0
             da0p4   ONLINE       0     0     0
             da1p4   ONLINE       0     0     0
             da2p4   ONLINE       0     0     0
             da3p4   ONLINE       0     0     0

errors: No known data errors

Then I ran zpool upgrade zroot and got:

This system supports ZFS pool feature flags.

Pool 'zroot' already has all supported and requested features enabled.

After that zpool status output stays the same what made me believe 
something is not right here.
-- 
Renato Botelho