Setting working directory to Default Working Dir for P4 build causes exception

2011-12-08 14:45:57,993 INFO [2-BAM::qwerty::Agent:pool-8-thread-1] [TaskResultBuilder] Process exception:
com.atlassian.utils.process.ProcessException: java.io.IOException: Cannot run program "/bin/sh" (in directory "/Users/brydie/dev/src/bamboo-hg/bamboo-homes/8085/xml-data/build-dir/113311745/REPO-P4MULTI-JOB1"): error=2, No such file or directory
    at com.atlassian.utils.process.ExternalProcess.start(ExternalProcess.java:286)
    at com.atlassian.utils.process.ExternalProcess.execute(ExternalProcess.java:408)
    at com.atlassian.bamboo.process.ProcessServiceImpl.executeProcess(ProcessServiceImpl.java:176)
    at com.atlassian.bamboo.plugins.shell.task.AbstractShellBuildTask.execute(AbstractShellBuildTask.java:62)
    at com.atlassian.bamboo.plugins.script.task.ScriptBuildTask.execute(ScriptBuildTask.java:53)
    at com.atlassian.bamboo.task.TaskExecutorImpl.executeTasks(TaskExecutorImpl.java:180)
    at com.atlassian.bamboo.task.TaskExecutorImpl.execute(TaskExecutorImpl.java:88)
    at com.atlassian.bamboo.build.pipeline.tasks.ExecuteBuildTask.call(ExecuteBuildTask.java:84)
    at sun.reflect.GeneratedMethodAccessor319.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:304)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
    at org.springframework.orm.hibernate.HibernateInterceptor.invoke(HibernateInterceptor.java:117)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
    at $Proxy484.call(Unknown Source)
    at com.atlassian.bamboo.v2.build.agent.DefaultBuildAgent.build(DefaultBuildAgent.java:198)
    at com.atlassian.bamboo.v2.build.agent.BuildAgentControllerImpl.waitAndPerformBuild(BuildAgentControllerImpl.java:103)
    at com.atlassian.bamboo.v2.build.agent.DefaultBuildAgent$1.run(DefaultBuildAgent.java:107)
    at com.atlassian.bamboo.build.pipeline.concurrent.NamedThreadFactory$2.run(NamedThreadFactory.java:50)
    at java.lang.Thread.run(Thread.java:680)
Caused by: java.io.IOException: Cannot run program "/bin/sh" (in directory "/Users/brydie/dev/src/bamboo-hg/bamboo-homes/8085/xml-data/build-dir/113311745/REPO-P4MULTI-JOB1"): error=2, No such file or directory
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:460)
    at com.atlassian.utils.process.ExternalProcess.createProcess(ExternalProcess.java:245)
    at com.atlassian.utils.process.ExternalProcess.start(ExternalProcess.java:283)
    ... 22 more
Caused by: java.io.IOException: error=2, No such file or directory
    at java.lang.UNIXProcess.forkAndExec(Native Method)
    at java.lang.UNIXProcess.<init>(UNIXProcess.java:53)
    at java.lang.ProcessImpl.start(ProcessImpl.java:91)
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:453)
    ... 24 more