title: gdb generate-core-file makes corrupted coredumps
body: <p>Ubuntu 10.10, GDB 7.2.
  I attach to an application, watch stacks in every thread, everything looks good. Do generate-core-file and try to open that coredump in gdb. No routines is shown in backtraces. </p>
  
  <p>I send SIGSEGV to the application and open this new coredump in gdb. Stacks are ok and verbose.</p>
  
  <p>Please tell me if you experienced a similar incorrect behaviour of generate-core-file.</p>