Merge block not functioning correctly for airtight doors
I came to build an airtight door on a station in space as I have done in the past, and found that when using a merge block to link the two grids together - the door grid is now converted into a station grid even when the merge is undone.
So the door won't move until the whole grid is converted into a ship.
An example of the behaviour, though not with the airtight door, is here using a simple piston-merge block to connect to a station grid merge block.
When the blocks merge, the piston-merge is now locked in place until the whole grid is converted to a ship, or you grind off the merge, and the top part of the piston (as seen here).
Obviously having station based custom airtight doors is a thing we use a lot, so this breaks those builds if we have to convert to ship every time to unlock them.