How to reproduction:
Step 1: make bad source code
Step 2: run "python -m py_compile bad_source_code.py"
Step 3: errors printed

It seems that this problem is introduced at issue 22640 (commit https://github.com/python/cpython/commit/2e33ecd7c9b0cac3efc6fcbdd4547fd086b4e2d1)
and it have not fixed yet.

variable 'quiet' is not defined in main function as far as I can see.

```
Traceback (most recent call last):
  File "c:\users\<USERNAME>\.scoop\apps\python\3.8.0\Lib\py_compile.py", line 144, in compile
    code = loader.source_to_code(source_bytes, dfile or file,
  File "<frozen importlib._bootstrap_external>", line 846, in source_to_code
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "c:/Users/<USERNAME>/AppData/Local/Temp/flycheckrIYLj4/test.py", line 25
    def calc_entropy(self):
    ^
IndentationError: expected an indented block

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "c:\users\<USERNAME>\.scoop\apps\python\3.8.0\Lib\py_compile.py", line 209, in main
    compile(filename, doraise=True)
  File "c:\users\<USERNAME>\.scoop\apps\python\3.8.0\Lib\py_compile.py", line 150, in compile
    raise py_exc
__main__.PyCompileError: Sorry: IndentationError: expected an indented block (c:/Users/<USERNAME>/AppData/Local/Temp/flycheckrIYLj4/test.py, line 25)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "c:\users\<USERNAME>\.scoop\apps\python\3.8.0\Lib\runpy.py", line 192, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "c:\users\<USERNAME>\.scoop\apps\python\3.8.0\Lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "c:\users\<USERNAME>\.scoop\apps\python\3.8.0\Lib\py_compile.py", line 218, in <module>
    sys.exit(main())
  File "c:\users\<USERNAME>\.scoop\apps\python\3.8.0\Lib\py_compile.py", line 213, in main
    if quiet < 2:
NameError: name 'quiet' is not defined

```