Index: src/main/java/hudson/scm/SubversionTagAction.java
===================================================================
--- src/main/java/hudson/scm/SubversionTagAction.java	(revision 20379)
+++ src/main/java/hudson/scm/SubversionTagAction.java	(working copy)
@@ -204,7 +204,7 @@
                             SVNCopySource csrc = new SVNCopySource(sourceRevision, sourceRevision, src);
                             svncc.doCopy(
                                     new SVNCopySource[]{csrc},
-                                    dst, false, true, false, "Tagged from "+build, null );
+                                    dst, false, true, false, "Tagged from "+getBuild(), null );
                         } catch (SVNException x) {
                             x.printStackTrace(listener.error("Failed to tag"));
                             return;
@@ -214,7 +214,7 @@
                     // completed successfully
                     for (Entry<SvnInfo,String> e : tagSet.entrySet())
                         SubversionTagAction.this.tags.get(e.getKey()).add(e.getValue());
-                    build.save();
+                    getBuild().save();
                     workerThread = null;
                 } finally {
                     cm.dispose();