SET time_zone='+0:00' when --utc is used. Fix another test that was a false-positive, revealed by this fix. Rename bugs.t to utc.t because it only has --utc tests.

bin/pt-heartbeat

@@ -5119,6 +5119,14 @@ sub main {
          $sth->finish();
          return ($delay, $hostname, $pk_val);
       };
+
+      # https://bugs.launchpad.net/percona-toolkit/+bug/1163372
+      # "pt-heartbeat --utc --check always returns 0"
+      if ( $utc ) {
+         my $sql = "SET time_zone='+0:00'";
+         PTDEBUG && _d($sql);
+         $dbh->do($sql);
+      }
    }
 
    # Do a little check just to make sure the table is there, so there's one last

t/pt-heartbeat/utc.t

@@ -55,7 +55,7 @@ sub start_update_instance {
       my $cmd = "$trunk/bin/pt-heartbeat";
       exec { $cmd } $cmd, qw(-h 127.0.0.1 -u msandbox -p msandbox -P), $port,
                           qw(--database test --table heartbeat --create-table),
-                          qw(--update --interval 0.5 --pid), $pidfile;
+                          qw(--utc --update --interval 0.5 --pid), $pidfile;
       exit 1;
    }
    push @exec_pids, $pid;