In newer game logs on game server one can find "Undo battle move" errrors.
[katzer@dhcppc2 games]$ grep "Undo move error" 20*/*/Colossus*.log
20200-20299/20286/Colossus0.log:SEVERE: Undo move error: no critter in F3
20200-20299/20286/Colossus0.log:SEVERE: Undo move error: no critter in E2
20200-20299/20286/Colossus0.log:SEVERE: Undo move error: no critter in E3
20200-20299/20286/Colossus0.log:SEVERE: Undo move error: no critter in D3
20200-20299/20286/Colossus0.log:SEVERE: Undo move error: no critter in D2
20200-20299/20286/Colossus0.log:SEVERE: Undo move error: no critter in D1
20200-20299/20286/Colossus0.log:SEVERE: Undo move error: no critter in C1
[katzer@dhcppc2 games]$
[katzer@dhcppc2 games]$ grep "Undo move error" 19*/*/Colossus*.log
19100-19199/19169/Colossus0.log:SEVERE: Undo move error: no critter in C1
[katzer@dhcppc2 games]$
[katzer@dhcppc2 games]$ grep "Undo move error" 18*/*/Colossus*.log
18000-18099/18097/Colossus0.log:SEVERE: Undo move error: no critter in D5
From 20286:
INFO: xxx's battle turn, number 1
Mar 5, 2012 6:51:54 AM net.sf.colossus.server.BattleServerSide$BattlePhaseAdvancer advancePhaseInternal
INFO: Battle phase advances to Move
Mar 5, 2012 6:52:06 AM net.sf.colossus.server.BattleServerSide doMove
INFO: Angel moves from X1 to D6
Mar 5, 2012 6:52:08 AM net.sf.colossus.server.BattleServerSide doMove
INFO: Titan moves from X1 to E5
Mar 5, 2012 6:52:10 AM net.sf.colossus.server.BattleServerSide doMove
INFO: Ranger moves from X1 to F4
Mar 5, 2012 6:52:11 AM net.sf.colossus.server.BattleServerSide doMove
INFO: Angel moves from X1 to F3
Mar 5, 2012 6:52:19 AM net.sf.colossus.server.CreatureServerSide undoMove
INFO: Angel undoes move and returns to Plains hex X1
Mar 5, 2012 6:52:20 AM net.sf.colossus.server.CreatureServerSide undoMove
INFO: Ranger undoes move and returns to Plains hex X1
Mar 5, 2012 6:52:20 AM net.sf.colossus.server.CreatureServerSide undoMove
INFO: Titan undoes move and returns to Plains hex X1
Mar 5, 2012 6:52:20 AM net.sf.colossus.server.CreatureServerSide undoMove
INFO: Angel undoes move and returns to Plains hex X1
Mar 5, 2012 6:52:20 AM net.sf.colossus.server.BattleServerSide undoMove
SEVERE: Undo move error: no critter in F3
Mar 5, 2012 6:52:20 AM net.sf.colossus.server.BattleServerSide undoMove
SEVERE: Undo move error: no critter in E2
Mar 5, 2012 6:52:20 AM net.sf.colossus.server.BattleServerSide undoMove
SEVERE: Undo move error: no critter in E3
Mar 5, 2012 6:52:20 AM net.sf.colossus.server.BattleServerSide undoMove
SEVERE: Undo move error: no critter in D3
Mar 5, 2012 6:52:20 AM net.sf.colossus.server.BattleServerSide undoMove
SEVERE: Undo move error: no critter in D2
Mar 5, 2012 6:52:20 AM net.sf.colossus.server.BattleServerSide undoMove
SEVERE: Undo move error: no critter in D1
Mar 5, 2012 6:52:20 AM net.sf.colossus.server.BattleServerSide undoMove
SEVERE: Undo move error: no critter in C1
Mar 5, 2012 6:52:23 AM net.sf.colossus.server.BattleServerSide doMove
INFO: Angel moves from X1 to D6
Mar 5, 2012 6:52:24 AM net.sf.colossus.server.BattleServerSide doMove
INFO: Ranger moves from X1 to E5
It's clearly that the undo actions are from previous battle.
In 19169, looks like a combination of double/wrong move due to delay and undo.
IN 1807, a combination of "null move" (which is not accepted any more by server) and undo from a move from previous battle/turn of same battle.
Nov 13, 2011 11:44:57 PM net.sf.colossus.server.BattleServerSide doMove
INFO: Gargoyle moves from C3 to D5
Nov 13, 2011 11:45:03 PM net.sf.colossus.server.BattleServerSide doMove
INFO: Gargoyle in Tower (1) hex D5 does not move
Nov 13, 2011 11:45:08 PM net.sf.colossus.server.BattleServerSide doMove
INFO: Gargoyle moves from E3 to D3
Nov 13, 2011 11:45:12 PM net.sf.colossus.server.CreatureServerSide undoMove
INFO: Gargoyle undoes move and returns to Tower (1) hex C3
Nov 13, 2011 11:45:12 PM net.sf.colossus.server.BattleServerSide undoMove
SEVERE: Undo move error: no critter in D5
Nov 13, 2011 11:45:24 PM net.sf.colossus.server.BattleServerSide doMove
INFO: Gargoyle moves from C3 to D5
Nov 13, 2011 11:45:26 PM net.sf.colossus.server.BattleServerSide$BattlePhaseAdvancer advancePhaseInternal
Fixed (most likely/hopefully) in r5117.
Error might still occur/visible in server logs for a long while, until all users will have taken coming release (probably) 0.13.1 into use.