Whirr launch for CDH4 MRv1 using deprecated mapred.child.java.opts property

Launching the cluster with the following properties, will install CDH4.2.0 MRv1 in all the nodes.
whirr.hadoop.install-function=install_cdh_hadoop
whirr.hadoop.configure-function=configure_cdh_hadoop
whirr.env.REPO=cdh4

However, after the launch of the cluster, the deprecated property, mapred.child.java.opts is set with default value as below,in mapred-site.xml
<property>
<name>mapred.child.java.opts</name>
<value>-Xmx550m</value>
</property>

To be used as :
mapred.(map|reduce).child.java.opts ie. mapred.map.child.java.opts and mapred.reduce.child.java.opts

To reproduce the error:
Running the map task or reduce task, more than the default heap size, creates OOME