Divide by zero error in MR AM when calculating available containers

When running a sleep job with zero CPU vcores i see the following exception

2015-04-30 06:41:06,954 ERROR [RMCommunicator Allocator] org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator: ERROR IN CONTACTING RM.
java.lang.ArithmeticException: / by zero
at org.apache.hadoop.mapreduce.v2.app.rm.ResourceCalculatorUtils.computeAvailableContainers(ResourceCalculatorUtils.java:38)
at org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator$ScheduledRequests.assign(RMContainerAllocator.java:947)
at org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator$ScheduledRequests.access$200(RMContainerAllocator.java:840)
at org.apache.hadoop.mapreduce.v2.app.rm.RMContainerAllocator.heartbeat(RMContainerAllocator.java:247)
at org.apache.hadoop.mapreduce.v2.app.rm.RMCommunicator$1.run(RMCommunicator.java:282)
at java.lang.Thread.run(Thread.java:745)