git_sort/lib: use correct class name for MutableSet
[BUG]
With latest python3.10, all git_sort scripts fails to start:
$ ./scripts/git_sort/series_insert.py
Traceback (most recent call last):
File "~/btrfs/suse/kernel-source/./scripts/git_sort/series_insert.py", line 34, in <module>
import lib
File "~/btrfs/suse/kernel-source/scripts/git_sort/lib.py", line 569, in <module>
class OrderedSet(collections.MutableSet):
AttributeError: module 'collections' has no attribute 'MutableSet'
[CAUSE]
From python3.3 and later, MutableSet needs to be referred using
"collections.abc.MutableSet", instead of just "collections.MutableSet".
After python3.9, the old compatible behavior seems to be removed, thus
causing above crash.
[FIX]
Try to import MutableSet from collections.abc first, if not found, then
try again from collections.
For v3.10 the first try should success, while on v3.4 I don't have any
system to test though. Hopes this would work.
Signed-off-by: Qu Wenruo <wqu@suse.com>