Remove most Python 3.6 special casing

src/ocrmypdf/__main__.py

@@ -15,7 +15,7 @@ from multiprocessing import set_start_method
 from ocrmypdf import __version__
 from ocrmypdf._plugin_manager import get_parser_options_plugins
 from ocrmypdf._sync import run_pipeline
-from ocrmypdf._validation import check_closed_streams, check_options
+from ocrmypdf._validation import check_options
 from ocrmypdf.api import Verbosity, configure_logging
 from ocrmypdf.exceptions import (
     BadArgsError,
@@ -34,9 +34,6 @@ def sigbus(*args):
 def run(args=None):
     _parser, options, plugin_manager = get_parser_options_plugins(args=args)
 
-    if not check_closed_streams(options):
-        return ExitCode.bad_args
-
     if hasattr(os, 'nice'):
         os.nice(5)
 

src/ocrmypdf/_logging.py

@@ -28,22 +28,14 @@ class TqdmConsole:
     This routes log messages through tqdm so that it can print them above the
     progress bar, and then refresh the progress bar, rather than overwriting
     it which looks messy.
-
-    For some reason Python 3.6 prints extra empty messages from time to time,
-    so we suppress those.
     """
 
     def __init__(self, file):
         self.file = file
-        self.py36 = sys.version_info[0:2] == (3, 6)
 
     def write(self, msg):
         # When no progress bar is active, tqdm.write() routes to print()
-        if self.py36:
-            if msg.strip() != '':
-                tqdm.write(msg.rstrip(), end='\n', file=self.file)
-        else:
-            tqdm.write(msg.rstrip(), end='\n', file=self.file)
+        tqdm.write(msg.rstrip(), end='\n', file=self.file)
 
     def flush(self):
         with suppress(AttributeError):

src/ocrmypdf/_validation.py

@@ -275,54 +275,6 @@ def check_options(options, plugin_manager):
     _check_options(options, plugin_manager, ocr_engine_languages)
 
 
-def check_closed_streams(options):  # pragma: no cover
-    """Work around Python issue with multiprocessing forking on closed streams
-
-    https://bugs.python.org/issue28326
-
-    Attempting to a fork/exec a new Python process when any of std{in,out,err}
-    are closed or not flushable for some reason may raise an exception.
-    Fix this by opening devnull if the handle seems to be closed.  Do this
-    globally to avoid tracking all places that fork.
-
-    Seems to be specific to multiprocessing.Process not all Python process
-    forkers.
-
-    The error actually occurs when the stream object is not flushable,
-    but replacing an open stream object that is not flushable with
-    /dev/null is a bad idea since it will create a silent failure.  Replacing
-    a closed handle with /dev/null seems safe.
-
-    """
-
-    if sys.version_info[0:3] >= (3, 6, 4):
-        return True  # Issued fixed in Python 3.6.4+
-
-    if sys.stderr is None:
-        sys.stderr = open(os.devnull, 'w')
-
-    if sys.stdin is None:
-        if options.input_file == '-':
-            log.error("Trying to read from stdin but stdin seems closed")
-            return False
-        sys.stdin = open(os.devnull)
-
-    if sys.stdout is None:
-        if options.output_file == '-':
-            # Can't replace stdout if the user is piping
-            # If this case can even happen, it must be some kind of weird
-            # stream.
-            log.error(
-                "Output was set to stdout '-' but the stream attached to "
-                "stdout does not support the flush() system call.  This "
-                "will fail."
-            )
-            return False
-        sys.stdout = open(os.devnull, 'w')
-
-    return True
-
-
 def create_input_file(options, work_folder: Path) -> Tuple[Path, str]:
     if options.input_file == '-':
         # stdin

src/ocrmypdf/subprocess/__init__.py

@@ -117,15 +117,7 @@ def _fix_process_args(args, env, kwargs):
     log.debug("Running: %s", args)
     process_log = log.getChild(os.path.basename(program))
     text = kwargs.get('text', False)
-    if sys.version_info < (3, 7):
-        if os.name == 'nt':
-            # Can't use close_fds=True on Windows with Python 3.6 or older
-            # https://bugs.python.org/issue19575, etc.
-            kwargs['close_fds'] = False
-        if 'text' in kwargs:
-            # Convert run(...text=) to run(...universal_newlines=) for Python 3.6
-            kwargs['universal_newlines'] = kwargs['text']
-            del kwargs['text']
+
     return args, env, process_log, text