Fix "Not in a step" exception with battle calc.

[asvitkine]

Change Summary & Additional Notes

Fix "Not in a step" exception w/ battle calc.

This fixes #10673, which can sometimes happen due to the cloned game state being used for battle calc simulation having a blank history. This change ensures that the cleared history has a round and step started.

Release Note

[asvitkine]

Hmm, not sure what's going on with the unit tests checker.

[asvitkine]

Still not sure why this makes Unit Tests hang.

[asvitkine]

OK, figured out the test hang issue. The new code in resetHistory() was trying to acquire a write lock, while in a block that was holding a read lock, causing a dead lock. Surprises there's no check in the lock code that verifies this.

Fixed by grabbing a write lock in the outer code. This should have been the case anyway, since state is being changed (e.g. swapping history, etc).

[codecov]

Codecov Report

Merging #10689 (26006c9) into master (0f52f7e) will increase coverage by 0.08%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master   #10689      +/-   ##
============================================
+ Coverage     27.66%   27.75%   +0.08%     
- Complexity     7967     7993      +26     
============================================
  Files          1210     1210              
  Lines         77805    77811       +6     
  Branches      10578    10578              
============================================
+ Hits          21526    21596      +70     
+ Misses        54345    54273      -72     
- Partials       1934     1942       +8     

Impacted Files	Coverage Δ
...main/java/games/strategy/engine/data/GameData.java	62.96% <100.00%> (+2.74%)	⬆️
...mes/strategy/engine/framework/GameDataManager.java	45.45% <100.00%> (ø)
...main/java/org/triplea/game/startup/SetupModel.java	66.66% <0.00%> (-33.34%)	⬇️
.../src/main/java/games/strategy/net/nio/Decoder.java	74.13% <0.00%> (-5.18%)	⬇️
.../changefactory/units/UnitDamageReceivedChange.java	90.47% <0.00%> (-0.44%)	⬇️
...va/games/strategy/engine/framework/ServerGame.java	0.55% <0.00%> (-0.01%)	⬇️
...a/org/triplea/game/server/HeadlessServerSetup.java	0.00% <0.00%> (ø)
...ategy/engine/framework/startup/mc/ClientModel.java	0.88% <0.00%> (ø)
...ategy/engine/framework/startup/mc/ServerModel.java	0.00% <0.00%> (ø)
.../engine/framework/startup/ui/ServerSetupPanel.java	0.00% <0.00%> (ø)
... and 13 more

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