This is not a bug.
This was a change initially slated for v1.3.0.7 to address some bugs, but looks like it made the v1.3.0.6 commit after all.
Updated the patch notes to reflect this.
- Summon Familiar: skill template updated to address issues with burst summoning. Skill is no longer instant cast.
- Summon Hellhound: skill template updated to address issues with burst summoning. Skill is no longer instant cast.
- Summon Briarthorn: skill template updated to address issues with burst summoning. Skill is no longer instant cast.