Fix MTR port calculation

Lately I experienced a great problem with the MTR port calculations.
Most (but not all) of the testsuite runs ended immediatelly with:
 |  mysql-test-run: *** ERROR: MTR_BUILD_THREAD number results in a port outside 5001 - 32767 (*****)
where the:
 |  (*****)
at the end is a string that contains the numbers used for the calculations.
The numbers were totally off, without any good reason why the calculation work that way.

I've reached MariaDB upstream and this patch was proposed in the ZULIP thread:
  https://mariadb.zulipchat.com/#narrow/stream/118759-general/topic/MTR.20--port-base

The upstream is hesitatnt to merge it righ away, but as far as I've tested,
it works well for me and what's most important, it unblocks the package builds.

mariadb-mtr.patch

@@ -0,0 +1,70 @@
+diff --git a/mysql-test/mariadb-test-run.pl b/mysql-test/mariadb-test-run.pl
+index 594e052a16e..6a274b2d597 100755
+--- a/mysql-test/mariadb-test-run.pl
++++ b/mysql-test/mariadb-test-run.pl
+@@ -1491,7 +1491,6 @@ sub command_line_setup {
+       mtr_warning ("Port base $opt_port_base rounded down to multiple of 10");
+       $opt_port_base-= $rem;
+     }
+-    $opt_build_thread= $opt_port_base / 10 - 1000;
+   }
+ 
+   # --------------------------------------------------------------------------
+@@ -1719,11 +1718,6 @@ sub command_line_setup {
+ # an environment variable can be used to control all ports. A small
+ # number is to be used, 0 - 16 or similar.
+ #
+-# Note the MASTER_MYPORT has to be set the same in all 4.x and 5.x
+-# versions of this script, else a 4.0 test run might conflict with a
+-# 5.1 test run, even if different MTR_BUILD_THREAD is used. This means
+-# all port numbers might not be used in this version of the script.
+-#
+ # Also note the limitation of ports we are allowed to hand out. This
+ # differs between operating systems and configuration, see
+ # http://www.ncftp.com/ncftpd/doc/misc/ephemeral_ports.html
+@@ -1734,10 +1728,14 @@ sub set_build_thread_ports($) {
+ 
+   if ( lc($opt_build_thread) eq 'auto' ) {
+     my $found_free = 0;
+-    $build_thread = 300;	# Start attempts from here
+-    my $build_thread_upper = $build_thread + ($opt_parallel > 1500
+-                                              ? 3000
+-                                              : 2 * $opt_parallel) + 300;
++    if ($opt_port_base eq "auto") {
++      $build_thread = 15000;
++    } else {
++      $build_thread = $opt_port_base;
++    }
++    $build_thread += ($thread - 1) * $opt_port_group_size;
++    my $build_thread_upper = $build_thread + $opt_parallel * 2;
++
+     while (! $found_free)
+     {
+       $build_thread= mtr_get_unique_id($build_thread, $build_thread_upper);
+@@ -1754,7 +1752,7 @@ sub set_build_thread_ports($) {
+   }
+   else
+   {
+-    $build_thread = $opt_build_thread + $thread - 1;
++    $build_thread = $opt_port_base + $thread - 1;
+     if (! check_ports_free($build_thread)) {
+       # Some port was not free(which one has already been printed)
+       mtr_error("Some port(s) was not free")
+@@ -1763,7 +1761,7 @@ sub set_build_thread_ports($) {
+   $ENV{MTR_BUILD_THREAD}= $build_thread;
+ 
+   # Calculate baseport
+-  $baseport= $build_thread * $opt_port_group_size + 10000;
++  $baseport= $build_thread;
+   if ( $baseport < 5001 or $baseport + $opt_port_group_size >= 32767 )
+   {
+     mtr_error("MTR_BUILD_THREAD number results in a port",
+@@ -2968,7 +2966,7 @@ sub kill_leftovers ($) {
+ sub check_ports_free ($)
+ {
+   my $bthread= shift;
+-  my $portbase = $bthread * $opt_port_group_size + 10000;
++  my $portbase = $bthread;
+   for ($portbase..$portbase+($opt_port_group_size-1)){
+     if (mtr_ping_port($_)){
+       mtr_report(" - 'localhost:$_' was not free");

mariadb.spec

@@ -229,6 +229,8 @@ Patch17:          upstream_5cc2096f93b7f130b36f8bc0fc43440db9a848e4.patch
 
 #   Patch13: bundle the FMT library
 Patch13:          %{pkgnamepatch}-libfmt.patch
+#   Patch14: make MTR port calculation reasonably predictable
+Patch14:          %{pkgnamepatch}-mtr.patch
 
 BuildRequires:    cmake gcc-c++
 BuildRequires:    multilib-rpm-config
@@ -764,6 +766,7 @@ rm -r storage/rocksdb/
 %if %{with bundled_fmt}
 %patch -P13 -p1
 %endif
+%patch -P14 -p1
 # The test in Patch 10 has been recently updated by upstream
 # and the test was disabled in the testuite run
 #   main.ssl_cipher     [ disabled ]  MDEV-17184 - Failures with OpenSSL 1.1.1
@@ -1221,14 +1224,6 @@ rm %{buildroot}%{_mandir}/man1/mbstream.1*
 %check
 %if %{with test}
 %if %runselftest
-# hack to let 32- and 64-bit tests run concurrently on same build machine
-export MTR_PARALLEL=1
-# Builds might happen at the same host, avoid collision
-#   The port used is calculated as 20 * MTR_BUILD_THREAD + 10000
-#   The resulting port must be between 5000 and 32767
-#   This is the same as using option "--build-thread" for the "mysql-test-run.pl"
-export MTR_BUILD_THREAD=$(( $(date +%s) % 1100 ))
-
 # The cmake build scripts don't provide any simple way to control the
 # options for mysql-test-run, so ignore the make target and just call it
 # manually.  Nonstandard options chosen are:
@@ -1249,7 +1244,7 @@ export MTR_BUILD_THREAD=$(( $(date +%s) % 1100 ))
   set -ex
   cd %{buildroot}%{_datadir}/mysql-test
 
-  export common_testsuite_arguments=" --parallel=auto --force --retry=2 --suite-timeout=900 --testcase-timeout=30 --mysqld=--binlog-format=mixed --force-restart --shutdown-timeout=60 --max-test-fail=5 "
+  export common_testsuite_arguments=" --port-base=$(( $(date +%s) % 20000 + 10000 )) --parallel=auto --force --retry=2 --suite-timeout=900 --testcase-timeout=30 --mysqld=--binlog-format=mixed --force-restart --shutdown-timeout=60 --max-test-fail=5 "
 
   # If full testsuite has already been run on this version and we don't explicitly want the full testsuite to be run
   if [[ "%{last_tested_version}" == "%{version}" ]] && [[ %{force_run_testsuite} -eq 0 ]]