GitResourceVariantTreeSubscriber relay on data that are added into GitSynchronizeDateSet. Such data contains repository, destination and source rev's using with we can determinate differences in particular file.

Passing empty GitSynchronizeDataSet will cause NPE in members() and getSyncInfo methods.

In case of git it is quite tricky to obtain subscriber because we don't have one main repository. Of course we can consider that in this case we'll be always comparing HEAD against HEAD (or origin/HEAD or maybe origin/master (?))

I'm not sure what the default behavior should be here :|