NullPointerException prevent global scm retrycount to apply

scm checkout retry only occurs on IOException
when SVNException occurs, this may be a transient error that a subsequent attempt to checkout won't hit
Users reported that this doesn't compile with Maven 2 anymore
[FIXED JENKINS-16160] plugin losing change information if previous build failed during svn checkout
Fail with useful error message instead of NPE, if subversion is not
installed
ignore
rolling forward after botched release
rolling forward after botched release
[maven-release-plugin] prepare release subversion-1.48
[maven-release-plugin] prepare for next development iteration
Merge branch 'master' into doCheckRemote-masterEnvVars