I discovered that yesterday in 1.7:
when you save from history during a (!) battle in xy, this battle somehow remains and if you start the save and you'll do something different, the engine asks you to finish the battle in xy first. Really weird...
Please describe in more detail what were doing leading to this and what you would expect.
From what I understand you selected a battle and after it has started you had a look at the history of the game. When you save the game then and reload it you should continue the selected battle and get a message in case you select a different one.
It's something different.
If you select history and right click at a certain point you'll get the option to "save at this point" (or something like that).
If you do that during a pending battle and load the save game, the above described error happens. Even if you are not attacking the territory you had pending during saving from history it will ask you to finish that battle first.
I can explain better what is happening.
There are 2 ways I think to cause bugs when saving a game from history.
First, if your CURRENT game is in a weird state, specifically any place where the current state of the game is saved in a delegate state (such as during the battle phase, the movement phases, etc), then this state information will get saved as part of the game save even if that information does not apply to the game save.
Second, if you are saving the game at a history point where there should be some delegate state, such as during movement or battle, then this information will not be saved because it is not actually recorded in history. Instead you will get whatever the current state is, which is probably nothing, or at least not related.
Unless the fix is a very light touch on the engine, I would probably not fix this bug, but instead provide better direction to the user who is making the save from history, about how to make the save without causing errors.