Generate a unique tmpdir for each server to avoid that they delete each others

temporary files at start up - see 'mysql_rm_tmp_tables'


mysql-test/mysql-test-run.pl:
  Create the servers tempdir before starting

mysql-test/lib/My/ConfigFactory.pm

@@ -104,10 +104,16 @@ sub fix_server_id {
 sub fix_socket {
   my ($self, $config, $group_name, $group)= @_;
   # Put socket file in tmpdir
-  my $dir= $group->value('tmpdir');
+  my $dir= $self->{ARGS}->{tmpdir};
   return "$dir/$group_name.sock";
 }
 
+sub fix_tmpdir {
+  my ($self, $config, $group_name, $group)= @_;
+  my $dir= $self->{ARGS}->{tmpdir};
+  return "$dir/$group_name";
+}
+
 sub fix_log_error {
   my ($self, $config, $group_name, $group)= @_;
   my $dir= dirname($group->value('datadir'));
@@ -182,7 +188,7 @@ sub fix_ssl_client_key {
 my @mysqld_rules=
   (
  { 'basedir' => sub { return shift->{ARGS}->{basedir}; } },
- { 'tmpdir' => sub { return shift->{ARGS}->{tmpdir}; } },
+ { 'tmpdir' => \&fix_tmpdir },
  { 'character-sets-dir' => \&fix_charset_dir },
  { 'language' => \&fix_language },
  { 'datadir' => \&fix_datadir },

mysql-test/mysql-test-run.pl

@@ -3816,6 +3816,10 @@ sub start_servers($) {
     mtr_error("Failed to copy system db to '$datadir'")
       unless -d $datadir;
 
+    # Create the servers tmpdir
+    my $tmpdir= $mysqld->value('tmpdir');
+    mkpath($tmpdir) unless -d $tmpdir;
+
     # Write start of testcase to log file
     mark_log($mysqld->value('log-error'), $tinfo);