In trying to build at work, when the ant process pulls dependencies for Tomcat, it would often hang and timeout, failing at that particular download.

I debugged some and realized that it was due to default value of get's "usehttpcaches" property set to true.  I edited the build file's trydownload target to be this:

  <target name="trydownload" if="trydownload.run" depends="trydownload.check">
    <!-- Downloads a file if not yet downloaded and the source URL is available -->
    <get src="${sourcefile}" retries="${trydownload.retries}" httpusecaches="${trydownload.httpusecaches}" dest="${destfile}" />
  </target>

and I added these in build.properties.default:

trydownload.retries=3
trydownload.httpusecaches=false

This would keep the default behavior implied with ant's get task.  Then I overrode that httpusecaches value in my build.properties file, and it reliably works all the time.  I left the retries value as it didn't change my results but thought it could prove useful for others.