0.12.6beta1: Comment out `tag_svn_revision` since it was causing build errors when empty.


git-svn-id: http://trac.edgewall.org/intertrac/log:/branches/0.12-stable@13128 af82e41b-90c4-0310-8c96-b1721e28e2e2
1.0.2beta1: Merged [13128] from 1.0-stable.


git-svn-id: http://trac.edgewall.org/intertrac/log:/branches/1.0-stable@13129 af82e41b-90c4-0310-8c96-b1721e28e2e2