Revert "Warn users when .boto might be outdated"

This reverts commit e2f35370f5a84676be3d3ff25426992820a22978.

Reason for revert: Potentially breaks https://source.chromium.org/chromium/chromium/src/+/main:build/fuchsia/gcs_download.py;l=34 

Original change's description:
> Warn users when .boto might be outdated
>
> Fixed: 1414152
> Change-Id: I887de64a72777c92413ee921099dd762361f6c5c
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4251897
> Commit-Queue: Aravind Vasudevan <aravindvasudev@google.com>
> Reviewed-by: Traian Captan <tcaptan@chromium.org>

Change-Id: Idd403b3054643b437ee165b8af2e775dc7e1abb6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4262468
Commit-Queue: Aravind Vasudevan <aravindvasudev@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
diff --git a/gsutil.py b/gsutil.py
index 042e4da..8b1e523 100755
--- a/gsutil.py
+++ b/gsutil.py
@@ -147,9 +147,6 @@
 
 def _is_luci_context():
   """Returns True if the script is run within luci-context"""
-  if os.getenv('SWARMING_HEADLESS') == '1':
-    return True
-
   luci_context_env = os.getenv('LUCI_CONTEXT')
   if not luci_context_env:
     return False
@@ -170,7 +167,12 @@
   if b'Not logged in.' in p.stderr:
     return _run_subprocess(cmd, interactive=True)
 
-  _print_subprocess_result(p)
+  if p.stdout:
+    print(p.stdout.decode('utf-8'), end='')
+
+  if p.stderr:
+    print(p.stderr.decode('utf-8'), file=sys.stderr, end='')
+
   return p
 
 
@@ -203,20 +205,9 @@
   return subprocess.run(cmd, **kwargs)
 
 
-def _print_subprocess_result(p):
-  """Prints the subprocess result to stdout & stderr."""
-  if p.stdout:
-    print(p.stdout.decode('utf-8'), end='')
-
-  if p.stderr:
-    print(p.stderr.decode('utf-8'), file=sys.stderr, end='')
-
-
 def is_boto_present():
   """Returns true if the .boto file is present in the default path."""
-  return os.getenv('BOTO_CONFIG') or os.getenv(
-      'AWS_CREDENTIAL_FILE') or os.path.isfile(
-          os.path.join(os.path.expanduser('~'), '.boto'))
+  return os.path.isfile(os.path.join(os.path.expanduser('~'), '.boto'))
 
 
 def run_gsutil(target, args, clean=False):
@@ -253,27 +244,12 @@
       gsutil_bin
   ] + args_opt + args
 
-  # When .boto is present, try without additional wrappers and handle specific
-  # errors.
-  if is_boto_present():
-    p = _run_subprocess(cmd)
-
-    # Notify user that their .boto file might be outdated.
-    if b'Your credentials are invalid.' in p.stderr:
-      print(
-          'Warning: You might have an outdated .boto file. If this issue '
-          'persists after running `gsutil.py config`, try removing your '
-          '.boto file.',
-          file=sys.stderr)
-
-    _print_subprocess_result(p)
-    return p.returncode
-
-  # Skip wrapping commands if luci-auth is already being
-  if _is_luci_context():
+  # Bypass luci-auth when run within a bot or .boto file is set.
+  if (_is_luci_context() or os.getenv('SWARMING_HEADLESS') == '1'
+      or os.getenv('BOTO_CONFIG') or os.getenv('AWS_CREDENTIAL_FILE')
+      or is_boto_present()):
     return _run_subprocess(cmd, interactive=True).returncode
 
-  # Wrap gsutil with luci-auth context.
   return luci_context(cmd).returncode