[core] No longer importing copy

* may now contain `LazyList`s
* resolves #31999

youtube_dl/YoutubeDL.py

@@ -5,7 +5,6 @@ from __future__ import absolute_import, unicode_literals
 
 import collections
 import contextlib
-import copy
 import datetime
 import errno
 import fileinput
@@ -1389,17 +1388,16 @@ class YoutubeDL(object):
                         'abr': formats_info[1].get('abr'),
                         'ext': output_ext,
                     }
-                video_selector, audio_selector = map(_build_selector_function, selector.selector)
 
                 def selector_function(ctx):
-                    for pair in itertools.product(
-                            video_selector(copy.deepcopy(ctx)), audio_selector(copy.deepcopy(ctx))):
+                    selector_fn = lambda x: _build_selector_function(x)(ctx)
+                    for pair in itertools.product(*map(selector_fn, selector.selector)):
                         yield _merge(pair)
 
             filters = [self._build_format_filter(f) for f in selector.filters]
 
             def final_selector(ctx):
-                ctx_copy = copy.deepcopy(ctx)
+                ctx_copy = dict(ctx)
                 for _filter in filters:
                     ctx_copy['formats'] = list(filter(_filter, ctx_copy['formats']))
                 return selector_function(ctx_copy)