Ensure that <packaging> is set in poms.

Previously our attempts to set packaging weren’t working at all and no packaging value was set in the pom one way or another. 

Fixes #2318.

Author: sjudd

scripts/upload.gradle

@@ -82,9 +82,12 @@ afterEvaluate { project ->
                     authentication(userName: getRepositoryUsername(), password: getRepositoryPassword())
                 }
 
+                pom.whenConfigured { pom ->
+                    pom.packaging = POM_PACKAGING
+                }
+
                 pom.project {
                     name = POM_NAME
-                    packaging = POM_PACKAGING
                     description = POM_DESCRIPTION
                     url = POM_URL