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>

gclient_eval.py

@@ -38,8 +38,8 @@ class ConstantString(object):
   def __eq__(self, other):
     if isinstance(other, ConstantString):
       return self.value == other.value
-    else:
-      return self.value == other
+
+    return self.value == other
 
   def __hash__(self):
       return self.value.__hash__()
@@ -304,13 +304,14 @@ def _gclient_eval(node_or_string, filename='<unknown>', vars_dict=None):
         raise ValueError(
             '%s takes exactly one argument (file %r, line %s)' % (
                 node.func.id, filename, getattr(node, 'lineno', '<unknown>')))
+
       if node.func.id == 'Str':
         if isinstance(node.args[0], ast.Str):
           return ConstantString(node.args[0].s)
         raise ValueError('Passed a non-string to Str() (file %r, line%s)' % (
             filename, getattr(node, 'lineno', '<unknown>')))
-      else:
-        arg = _convert(node.args[0])
+
+      arg = _convert(node.args[0])
       if not isinstance(arg, basestring):
         raise ValueError(
             'Var\'s argument must be a variable name (file %r, line %s)' % (
@@ -540,16 +541,20 @@ def EvaluateCondition(condition, variables, referenced_variables=None):
   def _convert(node, allow_tuple=False):
     if isinstance(node, ast.Str):
       return node.s
-    elif isinstance(node, ast.Tuple) and allow_tuple:
+
+    if isinstance(node, ast.Tuple) and allow_tuple:
       return tuple(map(_convert, node.elts))
-    elif isinstance(node, ast.Name):
+
+    if isinstance(node, ast.Name):
       if node.id in referenced_variables:
         raise ValueError(
             'invalid cyclic reference to %r (inside %r)' % (
                 node.id, condition))
-      elif node.id in _allowed_names:
+
+      if node.id in _allowed_names:
         return _allowed_names[node.id]
-      elif node.id in variables:
+
+      if node.id in variables:
         value = variables[node.id]
 
         # Allow using "native" types, without wrapping everything in strings.
@@ -562,16 +567,18 @@ def EvaluateCondition(condition, variables, referenced_variables=None):
             variables[node.id],
             variables,
             referenced_variables.union([node.id]))
-      else:
-        # Implicitly convert unrecognized names to strings.
-        # If we want to change this, we'll need to explicitly distinguish
-        # between arguments for GN to be passed verbatim, and ones to
-        # be evaluated.
-        return node.id
-    elif not sys.version_info[:2] < (3, 4) and isinstance(
+
+      # Implicitly convert unrecognized names to strings.
+      # If we want to change this, we'll need to explicitly distinguish
+      # between arguments for GN to be passed verbatim, and ones to
+      # be evaluated.
+      return node.id
+
+    if not sys.version_info[:2] < (3, 4) and isinstance(
         node, ast.NameConstant):  # Since Python 3.4
       return node.value
-    elif isinstance(node, ast.BoolOp) and isinstance(node.op, ast.Or):
+
+    if isinstance(node, ast.BoolOp) and isinstance(node.op, ast.Or):
       bool_values = []
       for value in node.values:
         bool_values.append(_convert(value))
@@ -580,7 +587,8 @@ def EvaluateCondition(condition, variables, referenced_variables=None):
               'invalid "or" operand %r (inside %r)' % (
                   bool_values[-1], condition))
       return any(bool_values)
-    elif isinstance(node, ast.BoolOp) and isinstance(node.op, ast.And):
+
+    if isinstance(node, ast.BoolOp) and isinstance(node.op, ast.And):
       bool_values = []
       for value in node.values:
         bool_values.append(_convert(value))
@@ -589,13 +597,15 @@ def EvaluateCondition(condition, variables, referenced_variables=None):
               'invalid "and" operand %r (inside %r)' % (
                   bool_values[-1], condition))
       return all(bool_values)
-    elif isinstance(node, ast.UnaryOp) and isinstance(node.op, ast.Not):
+
+    if isinstance(node, ast.UnaryOp) and isinstance(node.op, ast.Not):
       value = _convert(node.operand)
       if not isinstance(value, bool):
         raise ValueError(
             'invalid "not" operand %r (inside %r)' % (value, condition))
       return not value
-    elif isinstance(node, ast.Compare):
+
+    if isinstance(node, ast.Compare):
       if len(node.ops) != 1:
         raise ValueError(
             'invalid compare: exactly 1 operator required (inside %r)' % (
@@ -619,10 +629,10 @@ def EvaluateCondition(condition, variables, referenced_variables=None):
       raise ValueError(
           'unexpected operator: %s %s (inside %r)' % (
               node.ops[0], ast.dump(node), condition))
-    else:
-      raise ValueError(
-          'unexpected AST node: %s %s (inside %r)' % (
-              node, ast.dump(node), condition))
+
+    raise ValueError(
+        'unexpected AST node: %s %s (inside %r)' % (
+            node, ast.dump(node), condition))
   return _convert(main_node)
 
 
@@ -738,7 +748,8 @@ def SetVar(gclient_dict, var_name, value):
 def _GetVarName(node):
   if isinstance(node, ast.Call):
     return node.args[0].s
-  elif node.s.endswith('}'):
+
+  if node.s.endswith('}'):
     last_brace = node.s.rfind('{')
     return node.s[last_brace+1:-1]
   return None
@@ -880,12 +891,14 @@ def GetRevision(gclient_dict, dep_name):
   dep = gclient_dict['deps'][dep_name]
   if dep is None:
     return None
-  elif isinstance(dep, basestring):
+
+  if isinstance(dep, basestring):
     _, _, revision = dep.partition('@')
     return revision or None
-  elif isinstance(dep, collections_abc.Mapping) and 'url' in dep:
+
+  if isinstance(dep, collections_abc.Mapping) and 'url' in dep:
     _, _, revision = dep['url'].partition('@')
     return revision or None
-  else:
-    raise ValueError(
-        '%s is not a valid git dependency.' % dep_name)
+
+  raise ValueError(
+      '%s is not a valid git dependency.' % dep_name)