Calling a pre-commit groovy script independently elsewhere (not when located in my sub-repo) worked (using windows command line). I am using Windows 7.
But, calling a groovy script when it is located within a sub-repository fails with following error
Caught: java.net.MalformedURLException: unknown protocol: c
On further researching I found this https://issues.apache.org/jira/browse/GROOVY-7022
invoking scripts using fullpath was broken
I was using Groovy 2.4.3, updating it to Groovy 2.4.4 fixed my issue :)