CMake: Crash after trying to rename a build of a cancelled kit addition

Steps to reproduce:

• open a CMake project (I've used speedcrunch for this), follow the wizard to configure this one for a kit (Qt4 works for speedcrunch)
• try adding another kit on the 'Projects' view
  • brings up the CMake wizard again, I've selected a Qt5 kit which failed as Qt5 is not supported, so I've cancelled
  • nevertheless the kit is added to the Projects view
  • some buttons are still enabled (e.g. the Rename button for the current build)
• click the Rename button and Creator crashes as there's no current build that can be renamed

Expected result:

• a cancelled wizard should not add the selected kit