Kerbal Space Program

This bug has been fully reproduced in pure stock 1.4.5.

When a command seat is occupied and then decoupled from the focused craft through staging, the kerbal's personal chute will automatically fire when the stage separates from the main craft.
There is no indication that the personal chute has been added to the staging sequence for firing, and no way to control this. The kerbal chutes just always fire when the stage they are on releases from the main craft and is unfocused.

Expected: the chute should never automatically fire during the decoupling.

Reproduction:
Load the attached Chute Stage Test craft in the VAB, make sure both command pods have Kerbals, and launch.
EVA both Kerbals, and board them into the two seats.
Note that the root part is on the portion of the craft attached to the launch clamp, and that neither seat is on that part of the craft.
Hit space to decouple the part of the craft with both seats and Kerbals on it.
Note that the lower Kerbal's parachute deploys on the unfocused part of the craft that just got decoupled.
Use [ to focus that piece of the craft.
Hit space to decouple the upper probe core and top seat -- also note that the root part of this craft is below the decoupler.
Note that the Kerbal's chute deploys.

Important non-reproduction:
The attached Chute Stage Test3 craft is identical to the first, but has been rerooted to the probe core on the decoupled side of the craft.
If you repeat the above steps, neither of the parachutes deploy -- and the focus follows the pieces of the craft that are being decoupled.
So retaining focus prevents the bug from happening.

In the very short video below, there are two command seats on a basic craft with stagin. The seat on the side is part of the first stage to be fired, so the kerbal chute automatically "pops" as the craft is released. The command seat on top is separated by an additional decoupler, so it's on a later stage and does not fire when the first stage fires. However, it will also fire automatically when the associated staging is fired.

https://youtu.be/gyyPVwnJ8OM