Bug #44775 MTR fails to bootstrap mysqld on Windows in Pushbuild 2.

Suspected reason for the failure is that safe_process.exe already runs in a job that does not allow breakaways. 
The fix is to use a fallback -  make newly created process the root of the new process group. This allows to kill process together with descendants via GenerateConsoleCtrlEvent (CTRL_BREAK_EVENT, pid)

mysql-test/lib/My/SafeProcess/safe_process_win.cc

@@ -259,22 +259,37 @@ int main(int argc, const char** argv )
     the JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE flag, making sure it will be
     terminated when the last handle to it is closed(which is owned by
     this process).
+
+    If breakaway from job fails on some reason, fallback is to create a
+    new process group. Process groups also allow to kill process and its 
+    descedants, subject to some restrictions (processes have to run within
+    the same console,and must not ignore CTRL_BREAK)
   */
-  if (CreateProcess(NULL, (LPSTR)child_args,
+  DWORD create_flags[]= {CREATE_BREAKAWAY_FROM_JOB, CREATE_NEW_PROCESS_GROUP, 0};
+  BOOL process_created= FALSE;
+  BOOL jobobject_assigned= FALSE;
+
+  for (int i=0; i < sizeof(create_flags)/sizeof(create_flags[0]); i++)
+  { 
+    process_created= CreateProcess(NULL, (LPSTR)child_args,
                     NULL,
                     NULL,
                     TRUE, /* inherit handles */
-                    CREATE_SUSPENDED | CREATE_BREAKAWAY_FROM_JOB,
+                    CREATE_SUSPENDED | create_flags[i],
                     NULL,
                     NULL,
                     &si,
-                    &process_info) == 0)
-    die("CreateProcess failed");
+                    &process_info);
+    if (process_created)
+    {
+     jobobject_assigned= AssignProcessToJobObject(job_handle, process_info.hProcess);
+     break;
+    }
+  }
 
-  if (AssignProcessToJobObject(job_handle, process_info.hProcess) == 0)
+  if (!process_created)
   {
-    TerminateProcess(process_info.hProcess, 200);
-    die("AssignProcessToJobObject failed");
+    die("CreateProcess failed");
   }
   ResumeThread(process_info.hThread);
   CloseHandle(process_info.hThread);
@@ -312,6 +327,13 @@ int main(int argc, const char** argv )
     message("TerminateJobObject failed");
   CloseHandle(job_handle);
   message("Job terminated and closed");
+
+  if (!jobobject_assigned)
+  {
+    GenerateConsoleCtrlEvent(CTRL_BREAK_EVENT, process_info.dwProcessId);
+    TerminateProcess(process_info.hProcess, 202);
+  }
+
   if (wait_res != WAIT_OBJECT_0 + CHILD)
   {
     /* The child has not yet returned, wait for it */