Current patch version number (2.6?) isn't shown anywhere in the game or on the BattleNet launcher

The BattleNet launcher has a “Patch Notes” link for D2R (above the “Play” button) - clicking it shows only two tabs on my machine (for version 2.5.0 and 2.3). I’ve seen screenshots with much more version numbers including the latest patch that is supposed to be 2.6.

Below the “Play” button I can see “Version: 1.5.73090” that is somehow supposed to be 2.6 according to some random forum posts I found by searching for this number. Why doesn’t the BattleNet app show “Version: 2.6” there? I understand that a product may consist of several different components with different versioning strategies but we are talking about a public user interface with version numbers shared with the users.

Releasing a patch note with a version number that is completely different from that of the product makes zero sense. I guess other games (including previous Blizzard games) use the same public version number for the patch note and the product because it totally makes sense to do so.