Dragonstrike (and similar: Dragonmaw, Drakefist Hammer, Empyrean Demolisher) proc (spellid:21165) does not stack with Haste Potion (spellid:28507) in patch 2.5.4.42869.
Reference here-
(video they should stack at the top)
Per the reference, this was a bug in TBCC beta that was fixed. This has now broken again.
Video of interaction in 2.5.4.42869 for the lazy-
Hi Cleavis,
Thanks for the report. This isn’t a bug, technically, but this issue has an interesting bit of history and bears some explaining.
Between the launch of The Burning Crusade in Jan 2007 and the end of Patch 2.4.1 in May 2008, the proc from Dragonstrike and Haste Potions stacked, just as it has for the past 9 months or so of Burning Crusade Classic. In patch 2.4.2, a change was introduced that caused these two effects to share the same “exclusive” category. This caused these effects to no longer stack and this change persisted through to the end of The Burning Crusade. In patch 3.0.1, this change was reverted, and the weapon proc and potion again stacked.
While we were making the adjustment for Burning Crusade Classic patch 2.5.4 to change Dragonstrike from a Main Hand weapon to a One Hand weapon, we fixed an issue that incorrectly allowed the Dragonstrike proc to stack with itself (which was strictly incorrect behavior). A side effect of that fix was that it also restored the 2.4.2/2.4.3 behavior that prevented Haste Potions from stacking with the Dragonstrike proc effect.
All that being said, as this change only lasted for the final two patches of The Burning Crusade and was specifically reverted in Wrath, that leads us to believe that the original intent was for Haste Potions and Dragonstrike procs to stack. Just as we pulled in Tinnitus from Wrath of the Lich King and made adjustments to Druid energy regeneration as targeted #changes, we are also going to be sending out a hotfix within the next day or two to revert the part of this 2.5.4 bug fix that is preventing Dragonstrike and Haste Potion effects from stacking.
Don’t start Auctioning off your Haste pots or vendoring your Dragonstrike(s) yet. 
That is some very cool history. Appreciate the quick feedback and decision on this. Thank you, Aggrend 
Has this been hotfixed already? They seem to be stacking properly for me. Using Sinstats addon and both buff icons up at same time(haste potion and dragonstrike proc)