SCM polling broke for me after updating to: 1.605
Before this i was running 1.591

The log shows:
no revision found corresponding to svn://$SVN_SERVER/path; known: [svn://my.servername.com/path]

And it simply never triggered any of the builds for that reason. Apparently something changed in how or when the SCM paths get expanded.

Regardless of the change, isn't the fallback of triggering a build in case of "no revision found corresponding", a safer fallback strategy ?