Restore more_itertools.more, make importing concurrent.futures lazy

Co-authored-by: Jason R. Coombs <jaraco@jaraco.com>

Author: maciejp-ro

changelog.d/3091.misc.rst

@@ -1,4 +1,4 @@
-Removed unused ``more_itertools.more`` module from vendored ``more_itertools``
-package to avoid importing threading as a side effect (which caused
+Make ``concurrent.futures`` import lazy in vendored ``more_itertools``
+package to a avoid importing threading as a side effect (which caused
 `gevent/gevent#1865 <https://github.com/gevent/gevent/issues/1865>`__).
 -- by :user:`maciejp-ro`

pkg_resources/_vendor/more_itertools/__init__.py

@@ -1,3 +1,4 @@
+from .more import * # noqa
 from .recipes import * # noqa
 
 __version__ = '8.12.0'

pkg_resources/_vendor/more_itertools/__init__.pyi

@@ -1 +1,2 @@
+from .more import *
 from .recipes import *