runCommand: subversion: repository:
import (
  runCommand "head-revision"
    {
      buildInputs = [ subversion ];
      dummy = builtins.currentTime;
    }
    ''
      rev=$(echo p | svn ls -v --depth empty  ${repository} |awk '{ print $1 }')
      echo "[ \"$rev\" ]" > $out
      echo Latest revision is $rev
    ''
)