invoking scripts using full path broken in cygwin

I installed groovy using:

1. gvm install groovy 2.3.6

Then created ~/tmp/Test.groovy:

#!/usr/bin/env groovy

class Test {

static main(args)

}

If I try to run this as:

1. ~/tmp/Test.groovy

I get the following error:

Caught: java.net.MalformedURLException: unknown protocol: c
java.net.MalformedURLException: unknown protocol: c

Same error if I use a full path (i.e., /cygdrive/c/...). However, I can run it from my home directory using a relative path:

1. tmp/Test.groovy

This runs fine and prints "testing".

I installed groovy 2.2.2 using gvm and can run the same script no problem using ~ or the full path.