boot-qemu.py: Flush the qemu command print to ensure proper ordering

When writing boot-qemu.py output to a file, the command print will end
up at the end, rather than in the spot where it should be if it was
running interactively. Flush the IO buffers before running QEMU to
ensure the print is consistently where it should be.

Signed-off-by: Nathan Chancellor <[email protected]>

Author: nathanchance

boot-qemu.py

@@ -185,7 +185,8 @@ def _run_fg(self):
 
         qemu_cmd += [self._qemu_path, *self._qemu_args]
 
-        print(f"$ {' '.join(shlex.quote(str(elem)) for elem in qemu_cmd)}")
+        print(f"$ {' '.join(shlex.quote(str(elem)) for elem in qemu_cmd)}",
+              flush=True)
         try:
             subprocess.run(qemu_cmd, check=True)
         except subprocess.CalledProcessError as err: