Description of problem:
When saving changes done to the data model, user sometimes get Error modal with message "User <user> updated current project default://master@<repository>/<project> data model." and choice to "Re-open" or "Ignore".
Changes are saved always.
No other user is working with the product at all, in any way, at the same time.

This does not happen always, it tends to happen more for larger projects (bigger data model) and when repeating the change-save sequence without delay.
(Waiting a bit more before hitting the Save button seems to have improved things.)
Looks like something related to the incremental build and Data Modeler regenerating the sources, but that is just a wild guess.
Server log is clean. Whether the data model is simply saved or I get the Error modal when saving, it always contains only this, in the same order (received inc. build request -> inc. build request being processed -> KieModule added):

12:02:01,558 INFO [org.guvnor.common.services.builder.ResourceChangeIncrementalBuilder] (Thread-103) Incremental build request received for: default://master@bpms-assets/guvnor/src/main/java/guvnor/bugs/datamodeler/Ref1.java (deleted).
12:02:01,569 INFO [org.guvnor.common.services.builder.ResourceChangeIncrementalBuilder] (EJB default - 9) Incremental build request being processed: default://master@bpms-assets/guvnor/src/main/java/guvnor/bugs/datamodeler/Ref1.java (deleted).
12:02:03,041 INFO [org.drools.compiler.kie.builder.impl.KieRepositoryImpl] (EJB default - 9) KieModule was added:MemoryKieModule[ ReleaseId=org.jboss.qa.brms:guvnor:2.0]

Steps to Reproduce:
1. Change the data model.
2. Save the changes.
(3. Repeat if necessary.)