More coding style cleanup

Fixing more issues found with pylint.  Some that were supposed to
have been fixed in the previous sweep (Ie0db839e) but were missed:

C0321: More than one statement on a single line
W0622: Redefining built-in 'name'

And some more:

W0631: Using possibly undefined loop variable 'name'
W0223: Method 'name' is abstract in class 'name' but is not overridden
W0231: __init__ method from base class 'name' is not called

Change-Id: Ie119183708609d6279e973057a385fde864230c3

command.py

@@ -123,6 +123,11 @@ class Command(object):
     result.sort(key=_getpath)
     return result
 
+# pylint: disable-msg=W0223
+# Pylint warns that the `InteractiveCommand` and `PagedCommand` classes do not
+# override method `Execute` which is abstract in `Command`.  Since that method
+# is always implemented in classes derived from `InteractiveCommand` and
+# `PagedCommand`, this warning can be suppressed.
 class InteractiveCommand(Command):
   """Command which requires user interaction on the tty and
      must not run within a pager, even if the user asks to.
@@ -137,6 +142,8 @@ class PagedCommand(Command):
   def WantPager(self, opt):
     return True
 
+# pylint: enable-msg=W0223
+
 class MirrorSafeCommand(object):
   """Command permits itself to run within a mirror,
      and does not require a working directory.