I can't find the section for bugs, so putting it in here.
A clan mate had a mine with the tunnel closing when somebody launched a domain seizure on it. Unable to get enough troops there to defend the pit, I advised him to refuse the domain and launch a seizure of the mine himself. When the domain was refused, the tunnel continued to close and was closed before the seizure got there. From example 2 of this bit of the wiki, I think the tunnel should have stopped closing:
Tunnel Closing.
EXAMPLE:
Player1, a Pit’s owner, began Pit’s Tunnel closing.
If Player2 seizes the Pit while the Tunnel is closing, the Tunnel will continue closing anyway.
EXAMPLE2:
Player1, a Pit’s owner, began Pit’s Tunnel closing.
Player2 launched a Re-Seizure attack.
Player1, having a presentiment of defeat, refuses the Pit; in this case the Tunnel closing will stop.