[Resolved] Whirr on OS/X fails to package from source

If you found this, you're trying to build Apache's Whirr by following these instructions and running into an error at this step:

mvn package -Ppackage

And the error looks like:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-assembly-plugin:2.2-beta-5:single (dist-assembly) on project whirr: Failed to create assembly: Error adding file to archive: /Users/jonathan/Projects/whirr-0.6.0-incubating-src/NOTICE-src.txt isn't a file. -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

The solution is:

cp NOTICE.txt NOTICE-src.txt

You're welcome!