BACKLOG-4194 - Regressions raised by code review
https://jira.jahia.org/browse/BACKLOG-4194 

Propagate some SCM-related exceptions upper:
https://devtools.jahia.com/fisheye/cru/AND-168#c6690
https://devtools.jahia.com/fisheye/cru/AND-168#c6692
https://devtools.jahia.com/fisheye/cru/AND-168#c6693