Check if current project is up-to-date

The build meta data for SCM are retrieved from the SCM server but there is no check if the checked out sources are up-to-date.

There should be a flag to force a failure or silently ignore the fact that the checked out sources are newer (local modifications) or older.

In the case of local modifications this should be added as a note to the full version such as "... (locally modified!)"
In the case of an older version (e.g. a checked out tag to be repacked) the local version should be considered to be added.