Major:
An svn url like 'svn://my.svn.server/my/project/${stream}' with ${stream} set to 'trunk' or 'branches/1.0' causes SVN poll to disable the build because parameter substitution has not been implemented on the part that checks if a repository location exists.

Minor (will probably be fixed with the above):
Also, when the build is started manually, Jenkins prints
"Location 'svn://my.svn.server/my/project/${stream}' does not exist"
Regardless of this warning, it continues to check out.