Issued a try run. Jenkins checks SVN and says there are no differences, then runs Maven. After Maven is finished, there is a stack trace:

...
Caused by: org.apache.maven.shared.release.scm.ReleaseScmCommandException: Unable to check for local modifications
Provider message:
The svn command failed.
Command output:
/bin/sh: svn: not found

at org.apache.maven.shared.release.phase.ScmCheckModificationsPhase.execute(ScmCheckModificationsPhase.java:109)
at org.apache.maven.shared.release.phase.ScmCheckModificationsPhase.simulate(ScmCheckModificationsPhase.java:154)
at org.apache.maven.shared.release.DefaultReleaseManager.prepare(DefaultReleaseManager.java:199)
at org.apache.maven.shared.release.DefaultReleaseManager.prepare(DefaultReleaseManager.java:140)
at org.apache.maven.shared.release.DefaultReleaseManager.prepare(DefaultReleaseManager.java:103)
at org.apache.maven.plugins.release.PrepareReleaseMojo.prepareRelease(PrepareReleaseMojo.java:211)
... 30 more

The funny thing is that Jenkins can use svn, but Maven cannot? Strange!