Looks like sventon have changed the commited revision parameter from commitrev
to committedRevision. In order to work with 1.4 and preserve compatibility with
1.3 versions both parameters (commitrev and committedRevision) should be present.

patch:
hudson-1.198/core/src/main/java/hudson/scm/browsers/Sventon.java
62,63c62,63
> return new URL(url,
String.format("diffprev.svn?name=%s&commitrev=%d&committedRevision=%d&revision=%d&path=%s",
> repositoryInstance,r,r,r,URLEncoder.encode(getPath(path))));
—
< return new URL(url,
String.format("diffprev.svn?name=%s&commitrev=%d&revision=%d&path=%s",
< repositoryInstance,r,r,URLEncoder.encode(getPath(path))));