When we move transaction coordinator to the next step, we increment the count of coordinators in the new step and decrement the count for the previous step.

However, in case of error during kWritingParticipantList, we will jump straight to
kWritingDecision, skipping kWaitingForVotes, leading to server status like that 

"currentInSteps" : {
    "writingParticipantList" : NumberLong(1),
    "waitingForVotes" : NumberLong(-1),
    "writingDecision" : NumberLong(1),
    "waitingForDecisionAcks" : NumberLong(0),
    "writingEndOfTransaction" : NumberLong(0),
    "deletingCoordinatorDoc" : NumberLong(0)
}