[TF2] If the Wrangler is not fully deployed, the Engineer may pick up their own buildings

[KalleKokosnott]

In general, the issue applies to players who use a level 3 Sentry Gun's rockets with the Wrangler, which is fired with the same button as picking up buildings.
The Wrangler allows the Engineer to control their own Sentry Gun, as long as the Wrangler is fully deployed. Though, if the player selects their Wrangler, but not controlling the Sentry Gun just yet, the Engineer may pick up their own buildings that are within their pick up range, if they click the secondary attack button. This may lead to unintentional hauling of buildings, which can be fatal in the heat of a moment during gameplay. Note that the player doesn't need to have a Sentry Gun built at all to reproduce the issue of hauling buildings with the Wrangler.

Steps for reproducing the issue:

1. Equip Wrangler in loadout, but not in hand.
2. Have an active building within pick up range and look at the building.
3. Select Wrangler as active weapon.
4. While the deploy animation for the Wrangler plays, use the secondary attack button to pick up the building (default "MOUSE2").

An example to point out, are players in MvM, who utilize the quick deployment MvM feature of buildings.
In the heat of the moment, they quickly deploy a level 3 Sentry Gun and attempt to manually control it with the Wrangler. If they reproduce the steps above, they may unintentionally pick up the Sentry Gun.
There are reasons how this can happen, like (A) hiding behind the Sentry Gun right after deploying it to shield themselves from damage and aggro, or (B) repairing their own Sentry Gun and then select Wrangler while holding secondary attack for Sentry Gun's rockets. There could be many other reasons as well.

A suggestion to fix this issue is to disable the Engineer's pick up function when the Wrangler is in hand.

Side note: a fully deployed Wrangler will still show the pick up prompt on a building, which is misleading, and may confuse new players.