Bug #56654 pb2 log is very hard to read

Added some more info in a number of fail cases
(re-commit for administrative reasons)

mysql-test/mysql-test-run.pl

@@ -586,13 +586,15 @@ sub run_test_server ($$$) {
 	  if ($test_has_failed and $retries <= $opt_retry){
 	    # Test should be run one more time unless it has failed
 	    # too many times already
+	    my $tname= $result->{name};
 	    my $failures= $result->{failures};
 	    if ($opt_retry > 1 and $failures >= $opt_retry_failure){
-	      mtr_report("\nTest has failed $failures times,",
+	      mtr_report("\nTest $tname has failed $failures times,",
 			 "no more retries!\n");
 	    }
 	    else {
-	      mtr_report("\nRetrying test, attempt($retries/$opt_retry)...\n");
+	      mtr_report("\nRetrying test $tname, ".
+			 "attempt($retries/$opt_retry)...\n");
 	      delete($result->{result});
 	      $result->{retries}= $retries+1;
 	      $result->write_test($sock, 'TESTCASE');
@@ -3094,7 +3096,8 @@ sub check_testcase($$)
 	    "\nMTR's internal check of the test case '$tname' failed.
 This means that the test case does not preserve the state that existed
 before the test case was executed.  Most likely the test case did not
-do a proper clean-up.
+do a proper clean-up. It could also be caused by the previous test run
+by this thread, if the server wasn't restarted.
 This is the diff of the states of the servers before and after the
 test case was executed:\n";
 	  $tinfo->{check}.= $report;
@@ -3136,6 +3139,10 @@ test case was executed:\n";
     # Kill any check processes still running
     map($_->kill(), values(%started));
 
+    mtr_warning("Check-testcase failed, this could also be caused by the" .
+		" previous test run by this worker thread")
+      if $result > 1 && $mode eq "before";
+
     return $result;
   }
 
@@ -3789,7 +3796,9 @@ sub get_log_from_proc ($$) {
   foreach my $mysqld (mysqlds()) {
     if ($mysqld->{proc} eq $proc) {
       my @srv_lines= extract_server_log($mysqld->value('#log-error'), $name);
-      $srv_log= "\nServer log from this test:\n" . join ("", @srv_lines);
+      $srv_log= "\nServer log from this test:\n" .
+	"----------SERVER LOG START-----------\n". join ("", @srv_lines) .
+	"----------SERVER LOG END-------------\n";
       last;
     }
   }