I recently used the "Tag this build" feature, which worked fine, but the
resulting paged has little bug:

Output:
-----------
Build #3

Tagging is in progress.

Tagging hudson.scm.SubversionSCM$SvnInfo@9caeb2 to
http://server/repos/customers/tags/project-name-3

Completed
-----------

I guess the "hudson.scm.SubversionSCM$SvnInfo@9caeb2" is wrong and should be
replaced with the <project name>#<buildno> or something like that.