chdir("$staging_directory")
     or undo(1);
system("svn", "update", "base")
     or undo(2);
...

sub undo 
{
  my $state = shift;
  if($state >= .. ) # highest one first
  ..
  if($state >= 2)
  {
     system("svn" .. ) # undo svn/update/base command
  }
  if($state >= 1)
  {
    chdir("-");  # undo chdir command
  }

   die "Got to level X: $!\n";
}