Pops merge with incorrect POP unit on promotion

[shenso]

When pops are promoted the size of the current POP unit is decreased, and either a new POP unit is created, or a POP unit of the target type is incremented. In the latter case the game does not seem to check if the target POP unit is matching in all respects other than pop type. This can lead to what is commonly known as the "craftsmen bug," i.e. pops assimilate into a different culture as they promote.

Guides to reproduce

• https://imgur.com/a/SqvLiCf
• https://www.moddb.com/mods/victoria-universalis/news/guide-to-performing-the-colony-to-state-exploit-and-craftsmen-glitch