Revert "fix tag modifying"

This reverts commit e03a9a3d2ec7362367dd02f271c8f60ae5fa76a4.
Revert "fix tag destruction"

This reverts commit a1616a0c9573f4d16f256eb748ccb6ba1a2b47b0.
Revert "remove 'failing' test"

This reverts commit 43702cd6a58f116ef91349e6360ea6efcfcfe15c.
Revert "fix Ticket#tags saving when nothing has changed"

This reverts commit 0c49dded3ddc4174ba46f2e0e2d85599c5235391.