Debugger listed although not executable and not recognized

Steps to reproduce:

• create at least one of the following files inside your PATH (or put the path of them into PATH) - make sure they're not executable
  • lldb
  • gdb
  • gdb-i686-pc-mingw32
  • lldb-xyz
• start Creator with clean settings
• go to Tools -> Options -> Build & Run -> Debugger and check the listed debuggers

Current result:

• the mentioned files are added as debuggers (although they're not executable and the type of the debugger is not recognized by Creator)

Expected result:

• they should be ignored if they're not executable