executing system
  level commands in Java versions earlier than 1.3 this task may have difficulty
  operating with a relative path in ANT_HOME. The typical symptom is an 
  IOException where Apache Ant can't find /some/working/directory${ANT_HOME}/bin/antRun
  or something similar. The workaround is to change your ANT_HOME environment
  variable to an absolute path, which will remove the /some/working/directory portion
  of the above path and allow ant to find the correct commandline execution script.
 
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