Reland "Drop py2 support in gerrit and git related files"

This is a reland of commit b5c7f4b46c3309d46e1796bce7fa83388af9bfd8

Original change's description:
> Drop py2 support in gerrit and git related files
>
> python3 is the only supported version of python in depot_tools.
>
> Bug: 1475402
> Change-Id: Ie4ee18d297081b3aa0206b8d7ce6461819bff0ca
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4809560
> Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>
> Commit-Queue: Gavin Mak <gavinmak@google.com>

Bug: 1475402
Change-Id: I194180494071777b7b9dd91a5c8edabbbf5484c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4811218
Reviewed-by: Joanna Wang <jojwang@chromium.org>
Commit-Queue: Gavin Mak <gavinmak@google.com>
diff --git a/git_common.py b/git_common.py
index 3079b02..245eea5 100644
--- a/git_common.py
+++ b/git_common.py
@@ -16,9 +16,7 @@
 
 def wrapper(func):
   def wrap(self, timeout=None):
-    default_timeout = (1 << 31 if sys.version_info.major == 2 else
-                       threading.TIMEOUT_MAX)
-    return func(self, timeout=timeout or default_timeout)
+    return func(self, timeout=timeout or threading.TIMEOUT_MAX)
 
   return wrap
 IMapIterator.next = wrapper(IMapIterator.next)