Revert "Use pylint 2.7 for depot_tools"

This reverts commit 22bf605bb63f8ff01aa7c1a2841718e3489b43d6.

Reason for revert: breaks gclient sync

Original change's description:
> Use pylint 2.7 for depot_tools
>
> This includes a few fixes for specific errors, and disables several new
> warnings introduced in this version, in order to allow for an incremental migration.
>
> Bug:1262286
> Change-Id: Ie97d686748c9c952e87718a65f401c5f6f80a5c9
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3400616
> Reviewed-by: Gavin Mak <gavinmak@google.com>
> Commit-Queue: Aravind Vasudevan <aravindvasudev@google.com>

Bug: 1262286
Change-Id: Ieb946073c7886c7bf056ce843a5a48e82becf7a5
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3413672
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>
diff --git a/git_map.py b/git_map.py
index d7514a4..e8d4513 100755
--- a/git_map.py
+++ b/git_map.py
@@ -31,7 +31,6 @@
 
 if sys.version_info.major == 2:
   # On Python 3, BrokenPipeError is raised instead.
-  # pylint:disable=redefined-builtin
   BrokenPipeError = IOError
 
 
@@ -69,7 +68,7 @@
 
 
 def _color_branch(branch, all_branches, all_tags, current):
-  if branch in (current, 'HEAD -> ' + current):
+  if branch == current or branch == 'HEAD -> ' + current:
     color = CYAN
     current = None
   elif branch in all_branches: