Use phing to copy a file to a directory with an unknown name

Use phing to copy a file to a directory with an unknown name

I'm unpacking a zip-file using the Unzip task of phing which creates a
path like /target_dir/comes_from_the_zip_and_can_vary.
I now want to copy a file, let's call it config into the unzipped
directory, with phing, without knowing the exact name of the directory
comes_from_the_zip_and_can_vary.
The only thing I know is, that the directory starts with comes_from_the_zip.
I haven't found a way to target a directory by regular expression.
Any idea how I would copy the config file into the directory?