apport-retrace doesn't check to see if a core file is bad

[Brian Murray]

The Error Tracker retraces do a first check of a core file before setting up sandboxes and downloading packages, however apport itself does not. Here's what the ET retracers do:

 650 # confirm that gdb thinks the core file is good
 651 gdb_cmd = [self.gdb_path, "--batch", "--ex", "target core %s" %
 652 core_file]
 653 proc = Popen(gdb_cmd, stdout=PIPE, stderr=PIPE,
 654 universal_newlines=True)
 655 (out, err) = proc.communicate()
 656 if 'is truncated: expected core file size' in err or \
 657 'not a core dump' in err:

It'd be good if apport-retrace itself did this check and we avoided ambiguous failures to retrace like bug 1760286. I mean it has a bad core dump but nothing in the bug report indicates that.