Hadoop Streaming: java.lang.RuntimeException: PipeMapRed.waitOutputThreads(): subprocess failed with code 127

So, my most recent problem was that my hadoop streaming job was failing, and the tracking url was listing this exception under "Failed/Killed
Task Attempts":

java.lang.RuntimeException: PipeMapRed.waitOutputThreads(): subprocess failed with code 127
 at org.apache.hadoop.streaming.PipeMapRed.waitOutputThreads(PipeMapRed.java:311)
 at org.apache.hadoop.streaming.PipeMapRed.mapRedFinished(PipeMapRed.java:540)
 at org.apache.hadoop.streaming.PipeMapper.close(PipeMapper.java:132)
 at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:57)
 at org.apache.hadoop.streaming.PipeMapRunner.run(PipeMapRunner.java:36)
 at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:358)
 at org.apache.hadoop.mapred.MapTask.run(MapTask.java:307)
 at org.apache.hadoop.mapred.Child.main(Child.java:170)

Digging around in the logs directory I found a fuller explanation:

env: groovy: No such file or directory
java.lang.RuntimeException: PipeMapRed.waitOutputThreads(): subprocess failed with code 127

My groovy script was failing to launch - presumably because groovy wasn't visible on the path. My hacked solution was to hardcode the path to groovy in my script:

#!/usr/bin/env /Users/user/Applications/groovy-1.6-RC-2/bin/groovy

And then, voila! It worked!