QbsProjectManager: All targets have a trailing '2'

Steps to reproduce:

• open qtcreator.qbs from QC's repository
• while parsing the project switch to Projects view -> Run Settings
  • all targets are listed correctly
• wait for parsing having finished
• switch to Projects view -> Run Settings
  • all targets are listed with a trailing '2' (although there's no other target with the same name without a trailing '2' (or a trailing '1'))

Note: If you have a second build config and switch between the first and the second you'll get the trailing '2' if the target had no trailing '2' and you're losing the trailing '2' if you had it.