Not certain it's actually needed.
Patrick raised the following on the mailing list:
I run into problems when executing 'mvn validate' with
simpleapp-archetype version 1.14.0 by following the documentation
The new mojo:buildnumber-mave-plugin generates the error message:
"Cannot get the revision information from the scm repository"
Obviously this error makes sense as I was not connected to any scm
during validation. To pass validation without connection to an scm, I
added the plugin parameter <revisionOnScmFailure> to the pom.xml in the
webapp directory (See my plugin configuration below). This seems to work
well so far.
Anyway I couldn't find any hint for that problem in the apache isis