Rebels besieging a hostile fort still receive an attacker terrain penalty

[Unbidregent]

Integrity​

I have verified my game files (on Steam)​

Yes

I have disabled all mods​

Yes

Required​

Summary​

Rebels besieging a hostile fort still receive an attacker terrain penalty

Description​

Playing as Castile, I discovered that pretender rebels in Granada still received a -2 terrain penalty when I attacked their army besieging the Granadan fort (whom I was at war with, i.e. the fort was NOT mine as I had just barely declared war)
I am unsure if this only applies to rebels or if it is true for all tags.

Steps to reproduce​

As a neutral party, declare war on another nation and attack a rebel army besieging THEIR fort in unfavorable terrain.
To confirm if this applies to all tags, do the same except replace the rebels with a third nation which is at war with the other nation.

Game Version​

1.36 (King of Kings)

OS​

Windows

Additional​

Bug Type​

• Other

Attachments​

Screenshot​