flake8: Suppress "F821 undefined name" inline for Python 2 names

All of the instances of this are related to Python 2 names that
don't exist in Python 3, and the warnings are raised when running
flake8 on Python 3.

All of these will go away once we completely remove support for
Python 2, so just suppress them inline. We don't globally suppress
the check so that we will still see legitimate errors if/when they
occur in new code.

Change-Id: Iccf955f50abfc9f83b371fc0af6cceb51037456f
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/255039
Tested-by: David Pursehouse <dpursehouse@collab.net>
Reviewed-by: Mike Frysinger <vapier@google.com>
diff --git a/main.py b/main.py
index abb99cc..3efb1c3 100755
--- a/main.py
+++ b/main.py
@@ -69,7 +69,7 @@
 from subcmds import all_commands
 
 if not is_python3():
-  input = raw_input
+  input = raw_input  # noqa: F821
 
 global_options = optparse.OptionParser(
     usage='repo [-p|--paginate|--no-pager] COMMAND [ARGS]',
diff --git a/platform_utils_win32.py b/platform_utils_win32.py
index c59db52..a628637 100644
--- a/platform_utils_win32.py
+++ b/platform_utils_win32.py
@@ -219,8 +219,8 @@
   if is_python3():
     return target
 
-  if isinstance(source, unicode):
-    return unicode(target)
+  if isinstance(source, unicode):  # noqa: F821
+    return unicode(target)  # noqa: F821
   return str(target)
 
 
diff --git a/project.py b/project.py
index 4af062a..d0bf465 100644
--- a/project.py
+++ b/project.py
@@ -52,7 +52,7 @@
   import urlparse
   urllib = imp.new_module('urllib')
   urllib.parse = urlparse
-  input = raw_input
+  input = raw_input  # noqa: F821
 
 
 def _lwrite(path, content):
diff --git a/subcmds/gitc_delete.py b/subcmds/gitc_delete.py
index 1011276..24d355a 100644
--- a/subcmds/gitc_delete.py
+++ b/subcmds/gitc_delete.py
@@ -22,7 +22,7 @@
 
 from pyversion import is_python3
 if not is_python3():
-  input = raw_input
+  input = raw_input  # noqa: F821
 
 
 class GitcDelete(Command, GitcClientCommand):
diff --git a/subcmds/upload.py b/subcmds/upload.py
index bc373b3..ba75a53 100644
--- a/subcmds/upload.py
+++ b/subcmds/upload.py
@@ -27,7 +27,7 @@
 
 from pyversion import is_python3
 if not is_python3():
-  input = raw_input
+  input = raw_input  # noqa: F821
 else:
   unicode = str